> Why can’t I be anti-vaccine and pro-choice?

That is not a box others want you to be put in. People want a justification for their views. There are the nazis and the people that think they are better than nazis (hint: not hard) and build their raison d'être around that. Well, nazis are quite unpleasant. Still, anything that might convince them of being wrong, which a position that cannot put you into firmly defined groups will do, will result in hostilities. Furthermore the tactics of both opponents will become the same with time. In the end there isn't even much difference between fascists and their opponents. Again, you fight the former most effectively by ignoring them and see the rights of people protected, that are target of the mobs. Those involved will quickly loose any conscience. It is the result if you believe you were wronged because people are somehow oppressing you. That is also when you loose your believe in meritocracy/fairness.

I don't think your perception of people not working in your interest is true. You should differentiate between public statements and deeds though. Meritocracy will still prevail in the long run.