I agree completely, but that's no reason to not engage in marketing at all. If you're not touching it, you're losing by default.

Dark patterns will yield great results, but you don't want to trick your users into buying something? There are alternatives besides having a website that's thrown together, doesn't pitch your product and requires the potential user to really, really want to try your product to suffer through the website.

It's true even in open source projects imho. If you want users to try and eventually use your software, it's good to make it easy for them.