Uhh.. how about the fact that almost no wallets/exchanges/no one uses it?

https://www.reddit.com/r/lightningnetwork/comments/190orn6/c...

There are a ton of outstanding technical issues that lightning has had that have just kind of been glossed over for the past half-decade because people start companies, raise funding, build small fortunes and their success is predicated on pretending those fundamental technical issues don't exist.

Don't get me wrong, L2 has its own set of technical issues. The complexity of L2 is high, and some of the currently popular L2 chains are not decentralized at all. But it has much higher usage and popularity than Lightning, and is being pushed forward strongly by the Ethereum Foundation itself.