It's not just now either, the porn industry was hugely influential in causing the adoption and spread of video (you know, on casette), movies and photography.
Indeed - I've heard it argued that the real reason that VHS won out over the technically superior Betamax format, was that Sony refused to license the Betamax technology to adult video vendors. Never dug into it, but it seems plausible.
Having just one deciding factor seems implausible. Straw that broke the camel's back? Sure. But calling it "the real reason" completely ignores every other relevant factor.