> the default expectation that authors will be promptly responding to new GitHub issues, bug reports and provide patches for free is insane.

I think there are many insane expectations out there, open source or not, so I don't personally see it that linked with the idea/ideal of open source.

> This is software support, it is a job, it should be paid.

Anything can be paid, nobody says otherwise. Some people prefer nobody pays for their source code (open source). Other people do support for free. And so on.

> The currently default model of having ... has nothing to do with open source and is not sustainable.

There were always arguments why open source will not be sustainable, many having some truth in them. But the current issue can be probably solved with some push-back on the speed of things or how attribution works. Something similar used to happen on some forums: you can't post a new thread for one month if you did not reply at least once without getting down-voted. For the current problem : if contributions are anonymous for the first 3 years of you contributing (if you are not banned) and your name becomes public only after, then all this "noise" for "advertisement" will die. Doubt this will discourage any well intentioned contributor.