I believe that's way too much effort for a project owners to create a community and then manage it.

Creating a community just takes a click. Managing the community is not necessary if a project owner doesn't want to have those features.

I believe it should be in the form similar to wikipedia or even "community notes" on X

This sounds like a frontend task. The "wiki" of a project could be the community description. But the regular user doesn't need to know this, they just open an editor to edit the project wiki.

except the fact anyone should be able to make changes and other members should be able to evaluate those edits

Yes, here is where roles come in. This is why I thought the communities structure can be a good fit for projects as well.