Well, for starters, a lot of game projects on this very community are using at least one of the aforementioned services. So this thread is 100% legit, even if in-group.
If even this community has a hard time from moving away from GitHub and other proprietary services, then who will?
If you don't like them and their technology don't use their services!
It's not that simple. There is no meaningful choice here. I don't get to choose what services other projects use.

Usually as an outsider, you have to pick the websites they have chosen.
If a project chooses to use a proprietary or broken service as the main communication platform, and I refuse to use it, I will be missing out on crucial information. So either I have to basically give up and join them anyways or refuse to use the service and miss out on a lot of information because I have to fall back to secondary channels. It's a lose-lose situation.
As for me, I still use GitHub, but with JS disabled. It still kinda sorta works for discussion. I stopped using Transifex, which forces me to go the more complicated way of building patches and sending them to the devs and hoping they did not update the translations in the meanwhile. It works, but it's tedious.
This might sound like nitpicking to some, but I think it's about being consistent and it IS relevant for projects that themselves pride as being “free software” or “open source”.

You have to admit the ultimate irony that a huge amount of free software projects are hosted on GitHub, which itself is
far from being free software.

Besides, there is always the danger that all these gratis services might screw you over big time. But that's probably a general problem with all web services that you do not own, not specific to libre vs proprietary. I hope you all keep backups of your data.

I know for some projects moving is hard, but my point is, I wish that more people
especially in our community would at least try.

Try to be proactive and work on libre alternatives to these services instead of just complaining about them

Dude! I just named a few websites.

Do they all suck so much you don't even recognize them? XD
I totally agree it's absolutely crucial to have libre software for core use cases, but there are already some choices available. But they're pointless if nobody uses them.

Maybe we could do better, but at least it's a start.