There's a long set of steps to making a tool mandatory in a development environment, but the final step should always, always be, "And you will find yourself on a PIP if you refuse to use the mandatory tools."
If people want to die on a hill that is demonstrably causing problems for all of their coworkers then let em.
If people want to die on a hill that is demonstrably causing problems for all of their coworkers then let em.