I have stood by many times for flights after I missed the ticketed flight. But, that was when I was younger and more of a risk taker. And before the airlines started expiring your ticket if not used the scheduled day of departure.
But, I never had a really big problem getting on.
I presume the airlines policy is that it is not a good idea to have the airport full of unhappy customers denied their flight because there was a traffic jam. Or whatever.
I don't think I would do this on purpose these days.