I agree that Mickey walking us down MS has and never will happen, and that is intentionally false marketing! Yes, I understand the literal meaning of what Disney is writing in the marketing materials; I just think it could lead one to believe they are getting something that they are not, and Disney Marketing has no problem if you do believe that and then go buy some tickets which are non-refundable.
And the possibility of a "sell out" directly says there is a limit on tickets, which does not occur on regular park tickets, so to me, that is a direct way of saying there will be a cap on the number of people admitted and it will be lower than a normal park day. Luckily for Disney's sake, they won't ever reveal what that cap is, and they can raise it any time they want to without anyone knowing the difference. That is, until you show up and compare your experience to your own or other's prior experiences with the same event in the past.
But I had the advantage of reading the experiences here, and having my own past experiences with these events too, before I bought my tickets this year. So I went in with eyes wide open Monday night. I got pretty much the experience I expected, and I wasn't disappointed because I knew what I was getting into this year. But I have decided we won't do the Halloween party at WDW again based on these experiences. I am sure there will be 20,000 people waiting to buy the tickets I won't be buying for the 2019 parties, so Disney should not fret...