There is nothing bad in learning from mistakes if encountered, but it is a wise and smart move to learn from others' mistakes so that you do not learn life the hard way. Doing that would help save time and the stress of starting all over again. One thing we should know is that mistakes are time wasted, although one has learnt from their mistakes if encountered, but the truth is that the time spent on that event that resulted to such an inicidence is already wasted so in that case, a wise man would learn from ones experience so that they do not encounter such and if they do, they already know how to remmedy the situation to save them time and stress.
You're correct on this, nothing is actually bad about learning from mistake just as you said but it hurts to learn from a mistake, is just like remembering your horrible past although learning from them to be a buyer version of yourself will go along way in reshaping you as a person and making you a better version of yourself but if you're willing to rewrite your wrongs, some person don't know that learning from mistake can be so devastating that's why some people don't like remembering there last because it makes them feel that aren't worth living or they actually messed up some opportunities that wouldve been of immensed help for their future growth.