the life of a kart engine (KT100 excluded) really is pretty much 10 years max. An old or out of voque engine may not be able to be raced nationally all over but it is not worthless, it just changes duties and becomes a hobby karter engine or a club engine. My son races Briggs and Stratton at home and an X30 on travel races. If we get to race 5-7 years on X30 then have to switch that is ok as we have gotten good use out of them and they will be sold to someone only racing club or running a hobby kart.
this sport is always evolving. It is not perfect but those of us that do it love it. and throwing out names and calling people assholes does not sit well at all, particularly when people have repeatedly tried to help answer questions. The best way to learn about the sport is to get involved in it. even if it is volunteering at a club as a corner worker.