Humble question from a noob: what is stopping someone from building Solana on top of Ethereum?

So I have just read this interview with a Solana validator, and to be quit honest – what a joke of a network (I honestly have no stake in either – I know it sound BS but take it or leave it). This network violates every tenet/principle of what we see as a blockchain.

https://laurashin.bulletin.com/178076467796725

But neverminded that now. My question is simple (and I am not technical enough (or even slightly) to know): what is stopping someone (or a group of people) from building a Solana-like network on top of Eth?

What I mean: a super-fast number of nodes which require some serious hardware (see Solana's validator requirements) and just speed up txs?

Will this need to be what is a called a roll-up? Will it lose composability?

Just curious about this.

Thanks!