I think the core issue is about trust.

I trust that the maintainers of the Python language & the Python Standard Library are not going to change their tuple-using APIs in a breaking way, without a clear signal (like a major-version bump).

I do not extend that same trust to other Python projects. Maybe I extend that same trust to projects that demonstrate proper use of Semantic Versioning, but not to others.

Using something other than tuples trades some performance for some stability, which is a trade I’m OK with.