You realize that the movie was controversial not because of its content, but because Guccione refused to submit it for rating, and tried to show it like any other film anyway? That was him breaking his responsibility (and, in some areas, the law).
So, yes, if they released it in normal theaters now, without having it rated, there'd be a problem. If they got it rated (I haven't myself seen it, I assume by reputation it deserves an X rating) and released it according to how such films are to be released, I don't expect there'd be any more problem than for any other X-rated movie.
Not so great an example, I'm afraid.
This is a better example.
However, there is still a complete logical failure in assuming that, since a thing could be done in the past, and you can't do it now, that's a failure, problem, or bad thing. You want me to start listing things that were deemed okay by society at one time, and are now not allowed? Because there's a ton of it with which I expect you'd have a hard time arguing against.
So, the fact that it happened in the past is not sufficient to justify that it should be possible today. As we go on, we learn that there's some stuff we just shouldn't do. You have to demonstrate that today, with our greater understanding, doing so would still be just as good an idea.
Moreover, as folks talk about Blazing Saddles, they forget that, even in the day it was released, supposedly an age that was so much more lax in what it allowed, it was Rated R in the US. You had to be 18 years old to see the thing without a parent.
And, the next question - is there any doubt in yoru mind that it could be made today and released on the internet for streaming? I have none. The internet is loaded with stuff deemed inappropriate by society.