I assume we're mostly talking in the context of programming languages, IDEs, and APIs. It probably doesn't matter if a team member starts using VSCode or Toad to code their SQL, so long as it's a widely trusted tool. However, I hope there arn't any teams who would start using something like a backup, issue tracking, or version control system without management's approval or knowledge, especially if there is already an official corporate standard that they're supposed to be using.