This is a bit like atheism. If you denounce your religion, they can't exactly drag you back into it. But that cuts both ways, if you are an atheist, you can't expect somebody religious to throw away their religion and marry you. The world doesn't owe you a marriage on your terms.

Caste is similar, if you throw away your caste and then go for marriage, a strong caste affiliate who doesn't subscribe to your world view may reject your proposal. This isn't discrimination, everybody has a right to marry somebody whom they feel they can be comfortable with.

You will be surprised how much 'pride' people take in their caste here in India. There are many caste specific festivals and traditions people observe. Almost all caste affiliates in India are willing participants.