As long as the maintainers are responsive to bug fixes and key feature requirements (since they aren’t accepting of outside contributors adding them), then this is fine, possibly even optimal in terms of quality.
The trouble comes in if they both don’t allow many outside contributions and at the same time they pull the same unjustified complaint of a lot of OSS and say because they aren’t paid for their time, they will prioritize what interests them rather than what resolves painpoints or missing features users need. You definitely can’t have it both ways.