I can speak as a GNOME developer—though not on behalf of the GNOME project as a community—and say: GNOME has not been “fine” without telemetry. It’s really, really hard to get actionable feedback out of users, especially in the free and open source software community, because the typical feedback is either “don’t change anything ever” or it comes with strings attached. Figuring out how people use the system, and integrate that information in the design, development, and testing loop is extremely hard without metrics of some form. Even understanding whether or not a class of optimisations can be enabled without breaking the machines of a certain amount of users is basically impossible: you can’t do a user survey for that.
So, yes: GNOME has been able to get by without telemetry. It would have made some things easier if we had it, and going forward it’s going to be exponentially harder to do without.