I'm not familar with Slay The Spire 2 (I played the board game. Liked that.).
But this "just buff the shit stuff" argument isn't the be-all end-all players think it is. Sometimes shit gets OP by accident and you have to bring it down. Usually players don't see this, but in the age of early access...
Payday 2 had this happen at least twice. Once with a regen build, and once with an armour build. It was basically playing with invincibility cheats on. Enemies couldn't kill you because your regen could outpace their damage.
Now, there is a discussion to be had about bringing back cheats, perhaps disabling achievements. But having a hold out game where players can't die will get boring pretty quick, and buffing other builds to also be invincible won't help.