Tech companies and their executives have, broadly, moved to align themselves with investors and adopted a posture of, often, disdain or outright hostility towards their users and employees. If tech companies don't value you, why provide value to them? If they back political positions hostile to your interests, why not return that hostility?
Even with that, the bots know it’s a real number. If you call T-Mobile and tell them to delete voicemail all together, the phone rings and rings and then it does a Click and hangs up.