Well I know of a few players hoping that schools are still looking...
Many DIIIs on the list - they're still filling roster spots. From our experience, these schools work hard all fall, winter and spring talking to kids, as they don't really get any "commitment" until the kid walks on campus in the fall.
As for the caveats - can't see how it hurts anyone if a football player isn't there... that just means all the REAL baseball players will stand out
Coaches with fall commitments - true, but everyone has recruiters they can send.
Early commits - again, more opportunity for those who haven't committed. And, as you said, signing for DIs happens in November. Not unheard of for players to change their minds.
It's tough to impossible for any showcase to guarantee that any school is going to show up. I guess as in every case - regardless of the season - it's pay your money and take your chances. If you plan to attend and see a school on the list that you're interested in, contact the coach and let him know you'll be there - tell him you saw his school was invited and you're hoping to be able to say hello.
My real point in posting is, don't lose hope if you haven't yet gotten the interest you were counting on. Keep plugging away - plenty of players don't make any decisions until senior year. If you can play fall ball or go to some fall and winter showcases, it's definitely worth the time.