We mostly agree on everything, although I think you left out a key word in the 2nd sentence.
What you're trying to say, 1:is that you believe that a printed time isn't always the letter of the law, its the spirit of the law. Yes, I agree; that's exactly what Disney was doing...in fact doing it to a fault.
Also, you're trying to say that 2a:cutting off people exactly at the end of the window will be hurt some travelers and create confrontations. I agree. Disney anticipated that some will not make it on time. So instead of initially coming up with a buffer for lateness...they had a much more loosely written directive for the CMs: If they "miss it", let them in. I understand why they would allowed this; there were trying to avoid confrontations and keep the peace. I can also understand how, over time, with the help of the internet, and CM's that for whatever reason were actually openly discussing this with some guests, this very liberal return exception may have gotten out of hand. Again, a guess, I don't know for sure.
And 2b
allowing these later returners doesn't distract (not benefit, the word you used) from another guests experience. I don't really know..I don't have access to Disney FP return data or line flow. Without real data I can't accept that premise. I can only guess that there was some reason why Disney posted, and thus encouraged, return times, and that most people actually did adhere to them. Without some verifiable data we're all just guessing at how the late returners were potentially affecting their system.
And finally, what you're trying to say 3: is that upcoming enforcement will change the way some people use it. Yes, I agree here too. I think that's the one thing everyone here agrees on.....that some will not be able to do it the way they did before. And that for some it will force them to choose between doing 2 popular things at the same time (like many others have always done). So,there's no doubt some will be affected.
I think the further argument to point 3 above, something I've discussed, is that those losing this secret benefit have no shoulders to cry on except others in their same boat. It's like the cable company was giving you HBO for free for years and finally stopped.