Yeah, I've read it. I didn't think much of it.There's an article in one of the Best of Trek anthologies called "The Disappearing Bum". It explores the reason why, in Star Trek IV, the Enterprise crew isn't mobbed by Star Trek fans who recognize them.
Star Trek the TV show doesn't exist the world of Star Trek. I don't really need an "explanation" for that, because that's how TV -- and fiction in general -- works. About the only TV show I can think of where the show also exists in the world of the show is The Monkees, and that's because they broke the fourth wall all the time.