Language learning, for example is a huge category. You can get completely mired trying to sort out "grammar translation" versus "direct method" or "comprehensible input" approaches, the pros and cons of spaced repetition vs extensive/intensive reading, phonology & minimal pairs, picking a textbook/grammar/dictionary -- it's a lot. I imagine there are some people who are broadly interested in language learning, and don't actually use that information to actually learn a language. It might be more fun to prepare to learn a language than to get into the challenging and less fun work of actually doing it. I see the parallels with "Gear Acquisition Syndrome".

True, and even more insidious than that can be consuming the actual learning material (e.g. textbooks), but not doing the required work to integrate it. I find that I need to do projects to properly learn something. Once I actually start doing things, I quickly identify the parts I knew in theory from reading about them but had never put to the test by solving real problems.