I discovered porn in the early to mid 80's prior to the existence of the Internet and my only opportunities to see such images was like
@paget54 said, limited to magazines & videotapes. Since in the beginning, any porn I obtained belonged to my father, that was the media choice of his generation as well, though I know he also had stereoscopic slides and 35 mm films, which didn't interest me as much as the books and tapes. I think for postcards you'd likely have to go back to my grandfathers' day, who both having served in WW II, I know French postcards were popular among servicemen, though I never personally saw them as both my grandfathers were very conservative and didn't discuss or admit such things.
Unlike today where there are tons of porn of all types just a mouse click away, because of my limited and sporadic access to the methods I had available there was many times all I had was my imagination and the memories of the images of was able to sometimes look at. Even after getting married and having access to actual sex, magazines and tapes, were still the only porn media available for much of the 90's. In fact, after we got our first PC with web access at the end of that decade, it was like a new world to me in being to see nekkid pictures without having to either find, "borrow" or buy it even if with 56k dial-up it seemed to take forever for the image to load enough to get to the good parts
.
So yeah, having knowledge of the pre-PC, pre-digital and pre-web days, I do sometimes think about the difference in porn access and do in a way appreciate more how easy it is now compared to the challenges of my generation, even if like you said it too much access might not be as healthy. I do think an overabundance can cause an addiction, although personally it has never been an issue for me as I've also always had access to a sexually adventurous partner. If anything, my viewing habits nowadays are rare and almost to the point I find it boring.