Isn’t the purpose of the Internet to challenge debate and share ideas/infomation with other people.

That is a good mindset to have, the problem is that you’re going to interact with a lot of people that do not argue in good faith and aren’t interested in debate as much as “winning” the argument using any tactic possible. These people and these arguments will suck your time, energy and sanity and give nothing in return. The best tactic for your own good is therefore to realise that you do not have to respect people that do not respect you, and spend your time and energy more wisely elsewhere.

I’m not saying don’t debate issues that are important to you btw, just be mindful of the circumstances where you do.