Because they don’t need to. My guess is that you just associate a lightning address with your username, and all Twitter does is present that to a wallet. This way twitter doesn’t need to do KYC, or ever hold any funds. They’re just the phone book.
(I used it back when it was in beta to buy something from blockstream, but that was it. Back then it was an extremely complex process.)
LN is an unnecessary solution to a made up problem. Other cryptos have proved that much much more transactions can be easily processed by merely increasing the blocksize.
12tb harddrive: $199.
Bitcoin blockchain is increasing at less than 100gb per year. The storage cost of 100gb is about $1.6
I'm sure people running nodes can spend more than 1.6 a year to store a bigger chain.