but it doesn't make sense to me that I'll never be able to use something that didn't always cause me a problem - and can be used by a large part of the population without issues
Not to be belligerent, but this could easily be a quote from a new member of AA.
I'll take issue with "can be used by a large part of the population without issue"
If we limit our discussion to the population of males who have known nothing but Internet porn (ages 12-30), I don't think we can safely say that they have no issues.
Many men who quit porn use find that it has affected them in many more ways than simply libido or sexual function. Huge sections of YBOP are devoted to this, as was the infamous TED talk by Phillip Zimbardo: The Demise of Guys
Whatever negative effects Internet porn causes, the number of guys affected is only increasing now that every adolescent has access to high speeds from day one. In the last year we have see a big jump in the percentage of rebooters who are teens (several with ED).
I'm going to piss a few guys off but there is no doubt Internet porn has psychological effects. How could it not? A kid starting Internet porn in 2012 is undergoing a form of brain training never experienced in history. Many counter with - "how is this different than the introduction of TV, or radio?"
Clearly the rapid fire, constantly searching, seeking dopamine, cannot be duplicated by any other medium. But the key factor is that an adolescence's main function to rewire its brain to everything sexual, so he can successfully reproduce. Internet porn is what his brain is wiring to - long before actual relationships.
Sorry for the rant. Back to you. You went only 45 days. It may seem quite long, but its quite short compared to nearly everyone else with porn-induced sexual dysfunction. I get emails from guys who continue to experience improvements beyond one year. Sexual function, yes - but also positive changes in perception, mood, motivation, etc.
The bottom line for me is that we do not know how many guys using porn are "affected". Porn-induced ED is the LAST stage of excessive porn use. What other porn-related symptoms have the developed? The only way to know is to quit for an extended period of time. Only a few are doing that.