Ethereum

There are a lot of debates around native rollups;

My first concern is whether we are reinventing sharding again and if this approach has the same problems that made us to revert sharding from Ethereum's roadmap. 

Trying to give answers for this.

Researcher
Co-author of EIP-7212 
Ex- @getclave

IMO the big advantage (and it's big) of native rollups over execution sharding isn't in the (current) implementation details, but in who is executing. Native rollups can be perused by anyone, allowing for quick parallel iterations by multiple teams, looking for good tech but also PMF. This much surface bigger area for innovation is more likely to succeed.