Earlier quoted context omitted.
If you believe that it's important for free software to use free software infrastructure (and you should[0]), then there is no choice but to do so. Infrastructure like GitHub is primarily a function of network effects and the only way to overcome them is to cast your lot appropriately. A maintainer who "doesn't care" if their infrastructure is proprietary is not doing a good job. [0]: https://drewdevault.com/2022/03/…
Seems an awful lot like perfection being the enemy of good. Github is and always has been a closed platform. It's also responsible for the largest explosion of open source activity from any single source in the last twenty years. Your argument relies on the assumption that the cost of migrating away from Github is a cost a FOSS project can pay and survive, which is a pretty heavy assumption as far as those things go.…
Many people write FOSS for many different reasons. Chasing popularity is among the worst, and using GitHub is a poor way of achieving it regardless.
GitHub is not good enough. Placing all of our FOSS eggs in a proprietary basket which is incompatible with FOSS values is an absolutely foolish thing to do. The alternatives exist and are equal to the task, if not exceptional.