On the other hand, there's been an endless parade of recent posts from other FOSS maintainers saying "we don't want your drive-by PRs": it's not hard to see people getting dissuaded from the whole dance of determining whether a project is receptive at all, then whether it has a reasonable number of hoops for outsiders to jump through.

Now, personally, when I file a bug report for a FOSS project I like to suggest an underlying cause and fix if I can figure it out, but I more rarely just submit a PR outright.

If I have to choose between no PR and a "drive-by PR" where the author doesn't understand the changes to have a discussion, or isn't available to do changes and expects me to "take it from there", then I'd much rather go with "no PR" for the sake of everyone.

On the third hand, pestering and shaming open-source maintainers because they don't accept your PR is how you get the XZ backdoor situation.

There is a different dynamic between this and that.