D&D 5e Ranger ready to play
Yeah, the ones I got were not direct invitations to games...usually people who'd been in some of the discussions with me on some of the Community Chat threads who liked the ideas I expressed and the way I expressed them, who were curious as to whether I would be interested in joining a game they were running...
Granted, a gray area, but they were also very plain that if their approach was unwelcome, they were sorry for having bothered me. And, I'll be honest...some of the coolest games I've been in on here were games where someone rMailed me and said, "I like the way you think...would you consider joining a game I'm starting?"
I don't know if that's a violation of the site policy or not, but I felt like it was a respectful way to try to get to know other players and expand horizons. Now, if they'd just sent me a link to a game out of the blue, with no preamble or explanation, I wouldn't have taken it anywhere near as well (and, yes, I've received game invitations like that, too...and laughed when I almost immediately saw the sender's name appear in the Chamber of Lost Souls, with a note from BigBadRon saying that, if you were going to illegally spam people with game invitations, it would be prudent to make sure that there were no moderators on your list of people to spam...)
So, I think (and this is not in any way official, it's my personal understanding of the policy) you can't just send out invitations to join a game...but if you start a conversation with someone and find things are going well, inviting them to join a game, if they're open to the idea, is okay. One is just spam, the other is actually making a sincere effort to discover if someone might be a good fit for your game and finding out if they are interested at all before you invite them...there's a level of personal courtesy in the second that is utterly absent from the first.