I think this is because there is just such a vast amount of information that as humans, each of us individually can only know so much of, and it creates a bit of an imposter syndrome to know how little you know, so many people feel the need to convince themselves that their little section of information is better or more important than other sections of information

It could also be the "well I had to spend years learning how to do what I do and you're using a tool you learned in 2 days so obviously it's not that easy and something HAS to be wrong"

I see that particular issue as the same as sending a spaceship to colonize a planet many light year away, but when they get there, there's been an established civilization for hundreds of years because they developed a better system of travel after the first one left. Same thing, person B got to the game later, but got their goal first, so person A thinks B isn't a real programmer because they didn't have to grind and struggle with inferior tools and tech.