It seems like you are asking in generalities, not specifics. If you really want my personal specifics, I could do that, but I do not think you would fid it useful. General, it is then; so here are my thoughts.
I think the bar is based not on reality (because in general one never meets these epic women in reality) but more of where these model's looks fall in the category of plastic-surgery enhanced superb physical specimens, the likes of which have not existed on this planet previously.
I own supercars and I own trucks. I find them each suitable for a given task, and do not mix the requirements. If I saw a hot chick in the supermarket, and posted a pic online, she would probably look very plain. Not because she is, but because her relative beauty to anyone I meet that day is 100% top end, but compared to photoshopped instagram models, she might be easily overlooked.
For example, I find the boobs too small, but that does not mean they are small for other people. If you get told you like butterfaces *shrug* fine, more for you, if the woman has what you like. Humans tend to gravitate beauty perception to simple facial features -- it helps us determine the person's intentions easier. But we all have our preferences. I like really big boobs and everything else comes in second. That does not define ,,The Perfect Boobs'' for everyone else. I am cool with that, seems like you are, too.
tl;dr: