long answer: the reason why the pokemon fanbase is such a disgusting cesspool is that most of the people there only play pokemon and/or bing bing yahoo shit and have no standards
ask a pokemonfag what video games he likes and odds are he'll just reply "well uh, pokemon and smash" and nothing else
people either don't know or don't want to know that their precious franchise sucks dick, so they "enjoy" their pokemon game even though it has the same story, mechanics, graphics, and whatnot
because if they leave pokemon behind, then what the hell are they going to play? if they leave pokemon behind, what are they gonna do with their pokemon-playing friends? they don't want to sit there and look at their friends playing the new pokemon games, battling, trading, and doing raids without them
pokemon is like a religion to these people. if you insult pokemon, you're insulting their entire personality
short answer: nostalgia and a lack of standards