I think some companies think, as long we're willing to have remote workers in the first place, why not get the cheapest? Obviously you can also pay someone in India less and provide them with "wildly higher quality of life than they would get anywhere in the Bay area from most perspectives".

My experience with Indian devs has been their English is as "proper" as anyone's, and their technical skill levels vary with about as much variation as in the U.S., where there are also plenty of not very good developers.

The thing is, once a company has decided to prioritize saving money on developers, they are probably willing to take devs who are really not very good to get cost savings (whether they realize it or not), and there are a lot of companies in India which exist to help them do that. If they wanted to hire not very good developers at cheaper rates in the U.S., they could easily do that too. Perhaps the people making the decisions fool themselves into thinking the rock-bottom-rate devs they are hiring in India are magically highly skilled, and somehow it's easier to fool yourself this way when they are on the other side of the world.