Really? As a man I've very rarely been treated that way on Reddit. Depending on the subreddit, it's often quite a toxic place. People scrutinise every single detail of my comments and often ridicule and return hateful remarks.
Having said that, I can imagine that posting as a woman would get disrespectful reactions if you're talking about topics that involve gender.
Also, try conducting an experiment like this in the real world. Walk around as a man for a week, and you'll quickly realise that you've been getting treated nicer and softer by strangers because you're a woman for your entire life.
Although on the flip side, you'll also realise that presenting as a man means you don't feel under threat by creeps, perverts and rapists and so on. So there are pros and cons to being either gender.