Because it invites more competition. Previously, if there was one vendor but they sucked, you just had to put up with them and use them anyway. Now, if they suck that much, someone's going to come along and eat their lunch.
We've all seen people outsourcing their thinking to AI. "Hey Claude, I need bug tracking which product should I use?" Claude then recommends Jira because it's the defacto standard as of 2026. This leads to Jira getting even more popular, leading to subsequent training data keeping it as the defacto standard.
Same issue for development technologies. React/Typescript will never ever go away thanks to coding agents.