I think those who switch to another programme after reaching super-duper elite in one are mostly those who fly enough to reach the super-duper level in more than one programme and who want to (re)qualify for both (all) programmes. There probably aren't very many who reach super-duper in one programme and then start spreading their travel so they get scattered miles but no status in a bunch of others.

Something the airlines could do to encourage "better loyalty" would be to do like KLM, i.e., whatever status miles you collect beyond what is needed for next year's qualification carry over to the following year. For example, 300k status miles qualify for 3 years' worth of 1K, EXP, etc.