Why did they react so massively, instead of dicking with patches?

Its fundamental issues were really just two things: it was a $40 game competing in a stale genre dominated by well established F2P games, and literally nobody even knew it existed in the first place. It had nothing selling it, Sony didn't do anything to manufacture any sort of enthusiasm, and the first time anyone heard about it was when there were a ton of "lmao you ever heard of Concord? No? Well get this, nobody's playing it! This game you haven't heard of, that nobody's heard of? It's dead, complete flop, what a joke amirite?" articles that sealed its fate because PvP games more than anything live on player confidence and investment (hence why F2P live service models have become basically mandatory for them, because anyone can "just try" those which helps keep the population numbers high enough that people keep playing).

It's still kind of weird they didn't shuffle it around and rerelease it as a F2P live service game, which it probably could have survived as, but honestly after getting the "dead game in the first 12 hours" rep it probably wasn't ever going to draw in crowds because all anyone associated it with was it being dead and unpopular.