There are a lot of "tricks" one can use to instruct others. If a "fear" (again, don't take fear literally - awareness with an edge - might be better) of either gear up or ground loop is instilled early then maybe instinctively, appropriate rudder input or gear down checks before landing will prevent these situations. The idea comes from a 20K plus hour instructor of mine who told me the "gear up myth" early on in my training. To this day, at FAF, 1000' AGL, 500' AGL and prior to touchdown, this fable makes me check my wheels (even on a fixed gear airplane) and thus, put off my gear up landing to the next flight.
Ok, I see what you're saying, but I still don't like it. I've seen this myth passed on so often, I'd rather it go away entirely, regardless of how educational it might be for some.
When I hear the saying I think of fate, losing control, inevitability, resignation, and all kinds of other negative traits for a pilot to believe in. I consider it a flawed way of thinking no matter how it's applied. I'd rather teach a person to take charge, make good decisions, and understand they control their own destiny rather than simply delay the inevitable for one more flight.
Beyond underlying mental attitudes from these myths, they don't do anything to teach a true understanding of the risks involved. Your example of checking gear down on a fixed gear aircraft is a perfect example of this. It's a memorized response that does nothing to enhance the safety of the flight. There's no thinking involved, only worrying.
When I do complex endorsement training with people I try to show them how gear up landings usually happen when a pilot is distracted or thrown out of their routine. I emphasize the importance of procedures and discipline, especially during arrival to an airport, to keep from getting distracted. That way when they're on their own and see themselves going down the accident chain...busy airspace, controllers talking, looking for traffic, dealing with pax...they become more aware of landing gear up and stick to the procedure. They see the risks, think about them, and do something about it. They don't have a blind fear of being "that guy" and needlessly check things over and over out of paranoia.
The same idea can be applied to tailwheel operations. Pilots shouldn't be concerned about a ground loop sneaking up out of nowhere and biting them. They should look at their experience in the aircraft, weather conditions, runway conditions, and any other pertinent factors to decide if it's safe or not.