Addressing common rollup misconceptions

Rollups are a temporary band aid fix — X, Y, Z blockchain can do it on L1 so they don’t need rollups

(by u/hehechibby, u/ec265)

X, Y, Z blockchain is still faster than rollups

No. Once again, whatever any L1 can do, a rollup can do it better long term. I’ll point out that there’s a wide-open design space with rollups, and some rollups will opt to have conservative rate limits — especially optimistic rollups. But with zkRs, they don’t have to — they can push past the limits of L1s as described in the article linked above.

Lack of composability is bad

(by u/Whovillage)

Fragmentation of liquidity is bad

(by u/Beef_Lamborghinion)

Rollups are centralized

(by u/Whovillage)

Casual users will never be able to execute the CEX — Ethereum mainnet — rollup journey / it’s too expensive

(by u/Whovillage, u/stevieraykatz)

It takes too long to withdraw from rollups

This is true for optimistic rollups — take 7 days to withdraw from rollup to L1 using the default bridge. However, as mentioned above, there are multiple options available that let you make a fast withdrawal for fungible assets. Of course, zkRollups don’t have this limitation. For NFTs, zkRs are thus a preferred solution.

Rollups will be obsolete after “Eth 2.0”

Firstly, “Eth2” is deprecated nomenclature. The two major upgrades coming to Ethereum next are The Merge which merges the consensus layer (previously eth2) with the execution layer (previously eth1) — so we’re all one Ethereum again! The next major upgrade after that is data sharding on the consensus layer side. Data sharding is actually focused on accelerating rollups. So, Ethereum L1 scalability will be limited for the foreseeable future, while rollups will scale through the roof!

Rollups are still too expensive

This is true, in the short term. Optimistic rollups like Arbitrum One and Optimistic Ethereum are reducing fees by 90%-95% currently, which while a huge improvement over Ethereum is still too expensive. With some optimizations like signature aggregation, better batching and calldata compression, this can be reduced to 99%. Indeed, zkRollups are already seeing 99% reductions getting fees down to the $0.10-$1 range even when L1 fees are high. dYdX is already doing transaction fees in the ~$0.10 for complex DeFi derivative trades — although this is abstracted away from the end users to be gas-free.

Rollup finality is slow

Rollup sequencers give you “soft confirmations” nearly instantly — for me this is ~0.3 seconds on average for a Uniswap trade on Arbitrum or Optimism. For most people, this soft confirmation is fine. But it’s true that L1 finality is often delayed, especially in the case of zkRs. StarkNet has a great solution with checkpoints achieving effective finality on the rollup side very quickly, at which point the finality is as fast as the L1 can finalize. As zk tech improves, Ethereum implements single-slot finality and data shards are staggered, we will see finality drop to a few seconds. You can also have a consensus mechanism on a rollup that finalizes fast — just like any L1 would — so you get the same experience, but additional security. But this gives up efficiencies gained from being a rollup.

Rollups are an Ethereum thing and bound by EVM and Solidity

Rollups are definitely not just an Ethereum thing. Indeed, Tezos is embracing a rollup-centric roadmap. Arthur Breitman, founder of Tezos, actually makes one of the best arguments for why rollups are the ultimate scalability solution, in tandem with data shards. NEAR is also designing for sharded data availability. Celestia is building a security & DA layer exclusively for rollups.

Why is Ethereum special, if you can deploy rollups elsewhere?

Rollups will leverage whatever is the most secure and decentralized L1 with the highest data availability that can support it.

Rollups are stealing traffic from Ethereum

Ethereum execution is fully saturated, and has had full blocks for years now. All activity on rollups is net additive. Now, some may argue sharding would have expanded Ethereum’s capacity — but rollups + data shards in tandem increase the overall capacity of the Ethereum ecosystem by several orders of magnitude more than the previous sharding solution.

Rollups are too complicated, no one will understand it

Might I just point out I’m writing this on the day that Arbitrum One has proven to be the fastest growing smart contract platform in history? In reality, the UX for using a rollup is identical to that of using an L1, as covered before. Users need not care about the underlying architecture — to them it’s just another smart contract platform. Do YouTube users care about what programming language it was written in, what OS the servers run on, what hardware the servers implement, what internet connection they use etc.? Of course not. Indeed, I expect things will improve significantly with smart contract wallets and centralized frontends.

When rollups get big enough they will just abandon the base chain and create their own blockchain

(by u/Whovillage)

There are no rollup tokens, so people won’t be invested in the ecosystems

This is not quite true. While there are many rollup projects in their early stage and do not yet have a token, I expect most rollups to eventually release a token. Many rollup projects do have tokens, and are using them in innovative ways — like Immutable X. Just another advantage for rollups over L1s — you can have unique and clever token and fee models.

It’s too expensive to compute a zero-knowledge proof

True, but by amortizing this over many transactions, the costs become negligible relative to gas paid for transaction calldata. Of course, we’re still in the early days of zero-knowledge tech, and we’ll see costs and time for computing zk proofs plummet over time. Software optimizations, GPU/FPGAs/ASICs, Moore’s Law, and growing adoption with more transactions means things will only get better for zkRollups, which have already proved to be sustainable.

Can NFTs transfer easily between L1 and rollups and between rollups?

(by u/Datacruncha)

You’re talking about the future, execution risks remain

This is absolutely true. Rollups are nascent technology, and it’ll take a couple of years to mature and live up to their potential. Things can go wrong. Fair enough, but I do make it very clear what the current shortcomings are and how they will be fixed in the future.



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Rants and musings on blockchain tech. All content here in the public domain, please feel free to share/adapt/republish.