I don't think that's entirely true. Seeking mastery does not imply being a master.

If you have only ever seen one pattern to solve a problem, trivial example of inheritance, and therefore do that to the best of your ability then you have achieved mastery to your ability. Once you see a different pattern, composition, you can then master that and master identifying when which is suitable.

Lack of mastery is just using inheritance despite seeing alternative patterns.

Naturally mastery also includes seeking alternative solutions but just because a codebase uses inferior patterns does not mean those that came before did not strive towards mastery, it's possible that they didn't know better at the time and now cannot get the time to revise the work.

There's always a juggling act in the real world.

Assume incompetence and not malice, and incompetence is not a state of being. A person without experience can be seen as incompetent but quickly become competent with training or experience, but the code they write still stems from incompetence.

Strive to see your previous self as incompetent (learn something new every day)