I mean does anything on your physical record IRL ever disappear? Like, if its a crime? No lol.
Point being is the warns are there to let us know that you have done something really dumb in the past, and if the warn system were to be revamped, then that means the super mingey people would just disappear for a while and then come back just to do the same crazy stuff all over again. It tells us what kind of person that player is. If they are new and have 0 warnings, then no need to warn on a first time offense. If they have 3 or 4 over the course of 2 years, then the chances of them breaking rules are going to be slim and if they did, they would just swallow some pride and take the warning.
If someone manages to get 20+ warnings between 3 months and a year, then the chances are we are going to be keeping an eye on them just to be sure that they dont continue to break the rules and even further, if they did, chances are they wouldn't be around much longer to begin with. Either way, at the end of the day the rules are in place for a reason and that reason is to keep people in check. If you dont want to follow the rules, then to put it simple. You won't be here long.