I guess that is what "leaders" and mentors are supposed to do; lead people around or away from problems. The fact that people feel like they are "chasing the latest fad every year" is in and of itself a problem. They obviously are missing out on the financial advantage stability provides and getting poor returns on their investments. A shop like that might be better off running on all junior staff. So, in my humble opinion, either the wrong people are in charge or employees are misplaced, which again, reinforces that the wrong people are in charge.

A piece of hilariously cynical advise I got from one of those people with decades of experience was, "If you can't change your workplace, then change your workplace." Which is to say, if you don't feel empowered to make changes, then you need to think about why you are there. Is your role simply to be a cog? Hopefully, you are still improving in some way, but if not, you can probably find a better use of your time.

Regarding your question (yikes). Things are very cyclical and problems tend to be recurrent in some form. Thus, things that are new tend to be like things that have existed and some old lessons still apply. Generally, I've tended to mentor on processes, expectations, and alternative techniques.