Oh, it definitely could be considered as evidence that Github is a better platform for code hosting than gitea, gogs, etc. However I think that the difference is popularity is far more likely to be caused by network effects around Github as well as Github's comparative age.

There are also other factors impacting a users's decision to choose one hosting platform/software over another unrelated to the functionality of the software, such as code licensing and self hosting capability.

In summary, popularity certainly can be an indicator of whether or not a software or service is worth using, but it's not a direct measure of the quality or robustness or whatever other factors you may care about when making a decision.