People should be putting rollaboards wheels out in the back as well, so it's hard to "blame FCM" for the unwashed masses offending you in this case.
And IME I am usually hanging onto my coat for quite a while before a FA offers to hang it, so it's not surprising that people end up putting them up top. Another case where blaming the passenger is misguided.
Reminds me of the "nice man" who informed me that I was putting my luggage in wrong and Fixed it for me. Of course I put it in that way because it blocks the bin if it goes in the way he knew it should go in the overhead bin won't close. LOL!
(As for the three pieces of carryon Mr DYKWIA had with him I am sure the GA just decided the fit he would have thrown wasn't worth it. Or maybe that's why he was so late boarding. I don't think it was a late connection at MCO
)
I do think Delta is missing a HUGE opportunity. When anyone (including a DM) shows up at the gate with the 25" oversize luggage they should take a page from the el cheapo carriers and charge you about $200. Skip FCM and go for baggage fees. I have seen so many people bringing way bags that are way too big or just too many bags through security in Atlanta because they know Delta will give them a free gate check. It's time to close that loophole!