If I changed every bit of software I dislike, I would have no time left for my actual job. Yeah, I get it, these volunteers found the time to work on this one project and therefore get more of a say about what changes will be made, but you know what? They also have to use other software, and they would not have time to work on something like Gnome if they were busy making changes to Wayland or the Kernel or whatever else.
Worse, in my experience, Gnome developers will turn down patches that do not align with their ideas about how things should work. I have had it happen to me, I have seen it happen to others -- even when we find time to change something, we cannot commit to maintaining our own private fork, and dealing with merge after merge or trying to keep up with a project that has as much activity as Gnome or Wayland. Obviously some patches need to be rejected, but in the case of Gnome I have found that rejection often comes down to their notorious "less configurability is better" attitude.
As for stopping using it, how does that work with critical packages like systemd? At some point you wind up having to ditch an entire distribution, with all its infrastructure and maintainers, just to get one use case to work. In some cases you are left with a choice between a project that has the features you need but has received no updates (including security updates) in years, or a project that does not have the features you need but is actively maintained. More often than not people will just give up on their use case, which in some cases means giving up on open source software entirely since that use case was the reason they were using open source in the first place. Some might think that is fine, users have the freedom to choose what software to run, but the fact is that fewer users means fewer contributors (including many people who make only the small but very important contribution of reporting bugs) and a less robust open source ecosystem.
They don't get "more of a say", they get ALL the say. This is the way of Free/Open Source.
As for stopping using it, how does that work with critical packages like systemd?
It works the exact same way. If you don't like it, don't use it. Simple as that.
The option always remains to change it yourself or stop using it. It's not as if it's bound to the hardware (Apple) or shipped with the machine (Windows). It's not a SaaS that may vapourise or change underneath you.
There's no way to force consensus in situations like this. The best you can do is force out those maintainers you don't like with a harassment campaign.