The thread is about people of the opposite sex messaging a person of romantic interest without reading the profile, ignoring the fact they meet none of the parameters.
I think it does depend on the dating site. I'm on 2 reputable (semi) paid for sites. It does happen there too, but not nearly as often. And sometimes they have checked but have missed one thingie that to me is important.
On a free site with lots of scammers and/or non-serious people you get it much more. That's why I'm not on free dating sites anymore. The paid for sites do help filter those out for a big part.
Myself, I never sent a message without having checked their profile, but I must admit I mostly check the things that are important to me: Height, education level, religion, smoking or anti-smoking. Height being the Nr1.
If these things are okay for me, then I read their profile text, not before.