I guess I feel something akin to that "true fan" BS quite often. But it isn't that I think I am better or a truer fan than someone else, in my cases, it is that I often find I am a fan of something entirely different from other people who are fans of things bearing the same name as things I am a fan of.
I started watching The Walking Dead last year, and really liked it. It prompted me to read the comics, which I really enjoyed despite not being a comic book kind of guy. But I only made it about ten issues in before getting distracted. I was really disappointed with season 2 of the TV show, and after the season finale I decided to pick up the comics again to get some of the bad taste out of my mouth. I started from the beginning again and now just a couple of weeks later I am on issue #70. I love it and I'm hooked! Now when someone mentions how mind bogglingly awesome the TV show is, it is hard not to want to say, "The TV show is crap! You should really read the comics..." This isn't because I am insecure, or because I want to prove I have better taste. I was genuinely very disappointed with the second season of the show, and have found the comics to be a pleasant addiction.
Another example is The Legend of Zelda. My first Zelda game was the original on the NES, my last Zelda game was Majora's Mask on the N64. While I loved it back in the day, I just have zero interest in anything with the Zelda name on it that came out after Ocarina of Time, its the same thing over and over again, but with more baggage and dumber things that don't seem to fit the games universe (steam boats, trains, robots). I recently encountered a young Zelda fanatic, and mentioned how much I like Zelda myself. Turns out the only game we've both played is Ocarina of Time. His favorite is some new one that I don't know anything about. My favorite (A Link to the Past, SNES) he tried to play but said it was so boring to him that he couldn't stand it. We are clearly fans of two different things and there is no common ground between us.
We could argue who is the "truer fan", which would essentially be arguing what is the real Legend of Zelda or the real Walking Dead. But it would be pointless. They're all the real or the better one to someone.
I think the reason there is so much of this lately, is that so much is recycled, adapted, rebooted, re-imagined, sequelled to death, etc. these days. Doctor Who, Star Wars, Star Trek, [insert just about any mainstream comic books title here], Planet of the Apes, BSG, and a million others that I am sure anyone reading this could add to the list off the top of their head. It is inevitable that any given fan of anything is sooner or later going to encounter something bearing the name of the series he loves that he finds to be far removed and completely untrue to the things that made him love it in the first place; and it is also inevitable that sooner or later he is going to encounter someone who loves those very things, and finds the stuff he likes to be archaic boring forerunners or prototypes to the things they fell in love with.