garlicnutter - I appreciate some of your earlier points, which I'll try and come back to. But this:
Masturbation, for men, is a very different sensation from sex. It's harder, faster, firmer and done at a different angle. A vagina feels pretty loose and squishy by comparison
is bollox, I'm sorry. Just as I would never claim to understand what it's like to have a vagina, you need to accept that I have a better idea than you what it's like to have a penis. I've had a fair bit of sex in my life and plenty of wanking. I've been in relationships where I've only been able to see the woman occasionally and have wanked the rest of the time, and it's never been an issue, ever. The only time I would find it an issue is if I wanked on the same day as having sex - then it would affect it.
Vaginas come in a glorious variety of shapes and sizes and yes, some are pretty loose and squishy. And of course that affects the physical pleasure of sex just as the size of a man's willy does. This however is massively affected by the woman's engagement with the process. It's not so much what she has as what she does with it. I should probably stop now...
What you're saying might be true of some extreme cases, but is likely just as much to do with not being used to sex as with too much wanking. I once knew a guy who was a virgin till he was 45. Then when he finally had sex, he couldn't come no matter what. Makes sense I suppose.
Men whose primary sexual activity is mastubation end up having a problem with PIV sex.
Yeah, OK. And did you know it also makes you go blind and gives you hairy palms? Sorry but that's about where this little nugget of medical wisdom belongs.
Porn use exacerbates the problem - the brain associates the feeling of sexual stimulation and release with the images, pretty much forgetting about the entirely different pleasures of sex with a warm-blooded human.
Again you're making the same mistake you made before, and that so many women make - assuming that there can only be one way a man's brain works in relation to sex, and if it's doing one thing on a Monday it can't possibly do something that apparently "contradicts" that on the Tuesday. But in this thread for just one example, the OP herself told us that her husband's porn use doesn't appear to affect sex between them.
I'm not making this up; it's a simplification of why porn addiction happens. You can easily find out about it on the Web.
Oh well it must be true then. 
There's are a couple of questions that I think are being overlooked here, or maybe answered with too much assumption. Eg:
- Is it that men are made sexually dysfunctional by porn, or just that some men are completely crap lovers, always have been and always will be?
- Where does the bizarre underlying implication come from, that before porn was so mainstream, men were all totally sensitive and considerate to their wives, and all women lived in constant sexual bliss?
Is our historical memory so poor that we've forgotten what sex was actually like for the housewives of the 40s and 50s? If you really want to know about women as property and men with no idea that sex can mean anything but self satisfaction, then forget about teenagers watching porn. Just ask my parents' generation, they know all about it, and they didn't need the internet.