This is probably the saddest article on Medium I've read, not to mention the worst dating advice I've ever heard.
You're confusing being nice with being a codependent people pleaser with no boundaries. That's on you, my friend. You don't have to turn yourself into a jerk to help your mental health or chances at love, you just need to have more self-respect and a spine. And don't kid yourself about jerks--they're not confident truth-tellers, they're usually bullies with crippling insecurity who decimate your self-esteem because they have none.
But go ahead and be one, if that's how you think you're going to win people over. I pray you meet someone who truly likes you for you, and wouldn't that be nice?