When I was young enough to be thinking of sex but not old enough to be actually doing it, photographic porn in magazines was just appearing. There were, I believe, 8mm loops from Scandinavia around at the time, but who had 8mm projectors? The magazines at this time were often stills taken during the filming sessions of these short movies. There were no rules for these magazines and loops, and therefore they were displayed without being sealed, and there were no age restrictions on purchase. They also covered beastility and under-age sex, and both were legal at the time.
The only real impact these magazines had on me was that I thought myself average in terms of penis size, because many of the actors were about my size and some were bigger. But as they weren't moving images, they didn't really have much effect on my sexual expectations. The actresses in these loops and pictures were generally attractive with natural flaws, so I didn't have unreasonable expectations of the female body. Women come in all shapes and sizes, and the only thing that turns me off is a woman who has 'let herself go'.
The introduction of the video cassette recorder opened the floodgates of porn, but by then I was sexually experienced so I took what I saw as being fantasy rather than reality. Also, '80's porn was generally heterosexual intercourse with some anal but not often, and not anything like what we see today. Indeed, I prefer some of those old movies that I still have, as they have character and plot and a bit of connection between actor and actress. By this stage the actresses were still attractive, and still not enhanced in any way.
I don't know how I would have coped if I was 21 or 31 now, rather than 51. Unreasonable sexual expectations derived from porn? Unreasonable expectations that all women are pin-up beauties? Probably. One thing I do find strange is the desire for some men, or perhaps a lot of men, to pound away at intercourse for lengthy periods of time. Maybe this is porn driven, or maybe it's from discussion forums like this. While I could last half an hour or more, I would get bored and sore from friction, and my wife would also be bored and sore. Either way, it's not much fun, and there's much more enjoyment to be had before and after intercourse, and intercourse only needs to last as long as it needs to last.