Is it honestly that big of a problem? It doesn't seem so to me.
Plus, what's wrong with someone giving their pitch? It's likely that they'll pitch and get no response. Or maybe they pitch, it intrigues someone, and a conversation is sparked from there.
The fact that some people are looking for a romantic partner doesn't automatically make them wicked, or pitiable, or weak. The vast majority of the planet will marry and have children. It's a normal desire.
Plus, we're meant to be Christians, right? There's no need for us to grind people down. Gentle reminders about the purpose of these boards are sufficient to redirect most people.