While I agree that variety is important, many people use this tool to play test their decks. As pikarom is a strong deck, it will inevitably be played more often. You can choose to be salty and leave these matches, but all you will accomplish is to deny yourself and your opponent a game. Alternativly, you can change your deck to be more competetive against pikarom.
Some examples of this:
I run a deck that focuses on Banett GX and zoroark. GX. As pikarom has become more popular, I have replaced psychic energy with rainbow energy in order to add 2 babybuzz into my deck. While I can normally discard them to ultra ball, mysterious treasure or zoroark, in the pikarom matchup, it swing my deck from heavily disfavored to about even.
Some changes you can make to almost any deck:
Run more stadiums: While you don’t need to be running sky pillar just for the matchup, it is the best one to beat tag bold gx. Pikarom is one of the decks that benefits most from thunder mountain so being able to get rid of it quickly can change games.
Run a copy of alolan muk: In most decks, the card cost is minimal, a ditto and the muk, but it can turn off most of pikarom support since it disables jirachi, zapados and zeraora. It also turns off many other less popular decks like meganium stall and zoroark.
Your last option is to build an entirely new deck. While facing pikarom with one deck over and over again can certainly be repetitive, facing it with new decks really isn’t.
The reason I feel compelled to fight this mentality of just leaving is that while it is slightly annoying in quick play, it is downright toxic in career. The time it takes to find a match in career is generally longer than quickplay and many people use surrendering to deny their opponent ink.
Please consider this the next time you are in a matchup you don’t like.
Good luck and have fun