What if it's the applicable (if not "optimal") tool that the developer is most familiar and productive with?
What do you even mean by "optimal"? Loads fastest? Fewest LOC? Lowest client CPU impact? Can be designed, built, tested, and deployed in the shortest amount of time?
Salience is a big part of proficiency. If you're productive and familiar with a tool, and it wouldn't be terribly important to your actual needs to optimize that aspect of things... then even in the situation where there might be a better tool out there, it'd be fine to stick with what you know.
But on the other hand, if you struggle with a tool because you're using it in the wrong context, and you're either not aware of that because you're missing the bigger picture... or you're aware of it but refuse to step away from dogmatic best practices to customize for the situation at hand... then that's a bad thing.
So, the question of whether or not to go and find "the best tool" is a matter of whether it's salient in the context of the problem you're solving (and a bit more generally, the kinds of problems you solve day to day)
So proficiency involves to some extent choosing what not to learn as much as it does what to learn.
What if it's the applicable (if not "optimal") tool that the developer is most familiar and productive with?
What do you even mean by "optimal"? Loads fastest? Fewest LOC? Lowest client CPU impact? Can be designed, built, tested, and deployed in the shortest amount of time?