It's often frustrating, but true. People like what they like, and humans have a tendency to wrap their identity around things they like. We join tribes, effectively. You'll get Marvel fans who rail about the weaknesses of DC and vice versa. Star Wars vs. Star Trek, Gobots vs. Transformers...I kid, nobody likes Gobots.
Anyways, you can create a Power Point presentation to show that the elements of the thing they don't like exist in the thing that they do all day long- they will reject it because there's some fundamental difference to them, even if they can't articulate it. People like what they like.
If you liked 4e, then someone saying "oh it was just World of Warcraft" or "every class was exactly the same" is going to annoy you, just like if you say that to a 5e fan that their game is "simple and bland, like oatmeal".
For a long time, I fought against the spread of disinformation; a lot of things people say about 4e are just parroted from others, to the point people who have never even so much as looked at a 4e book will repeat the same things about it!
It's been hard to come to terms with the fact that this is just human nature at work. Many people who have embraced 5e want it to be the greatest version of D&D ever, and will denigrate other games to prove that their preferred vision is better, all the while blissfully ignoring it's flaws (and the same is true for fans of every edition ever, including 4e!).
The thing you like is a shining pinnacle of human achievement, the thing you don't like is hot garbage, lol. Naturally, this isn't true for all humans- individuals tend to be a lot more nuanced about their likes/dislikes, and you might even run into those mutants who like 4e and 5e! But it's common enough, regardless.
The thing to keep in mind is, the pendulum swung before, and it will likely swing again. Attitudes shift, ideas change, and what were once amazing ideas can become dated and old-fashioned. So here's to 6e, which fans of 5e and 4e will hate equally, so we can once again live in harmony!