A project that is centralized in Vitalik hands, was premined and was rolled back like Ethereum blockchain, is not a decentralized project and blockchain.
If Ethereum can not be decentralized, other altcoin projects and blockchain are only more centralized than Ethereum.
Just because ETH is centralized (even more so with PoS), it doesn't mean that every altcoin is centralized. That's a bit dismissive, don't you think?
Are Litecoin, Monero centralized? Just to name a few...
Regarding Lightning, necessity is the mother of invention.
When on chain transactions are dirt cheap, there is absolutely no reason to use L2:
https://litecoinspace.org/Bitcoin was like that 15 years ago...
If Litecoin became really popular, then it would face the exact same scaling issues.
There will always be a reason to use an off-chain layer on top of Bitcoin that utilizes actual Bitcoin transactions. I believe for those altcoins users that want Bitcoin HODLers to use their chains, prepare to be disappointed if your network won't incentivize HODLers with earning more units denominated in Bitcoin. Your network needs the liquidity more than Bitcoin needs your smaller liquidity. Plus if there isn't a bridge that doesn't rely on third parties to convert Bitcoin and use your chains, then let the "necessity is the mother of invention" build one.