What I've noticed in many of these meetups created for other people to mingle, is that a lot of people who drop by and don't have a loneliness problem, make the atmosphere worse for everyone else who does. Instead of fostering genuine connections, they just "don't see the issue" and shoot down genuine attempts of others (who might be introverts, shy, whatever) to connect. Such a thing is completely out of place, because the whole motivation for said meetup is to get people to know each other.
I have started placing notices like "if you have friends, don't come" lol, which is a bit controversial but actually upgrades the experience. An analogy, imagine a married guy dropping into a singles dating event to talk about how great a relationship he's in and giving "tips to survive a marriage" and whatever (and also, if it is that good, then why are you here?). You get the idea.
And I also agree with your last sentence.