>>35462746This is like asking why all primeape evos are angry mandrills with some variation of spiked collar/wrists, or why there are a million grass/fire pepper or normal/ghost schrodinger cat fakemon.
The moment an idea gains popularity, everybody that thinks they can add their own spin to it will try, and there's absolutely nothing wrong with that. We might have a million eeveelutions that look the same, but SOME of them necessarily have to be the best of the whole bunch or appeal to the most people, case in point, the picture you mention. I don't agree with all the designs there either (the rock, normal and ghost ones mostly), but the artist drew it at the right time and with enough level of technical quality so that it became the standard for what many other artists take inspiration from. Maybe had a different picture by a different artist depicting eeveelutions closer to the 3 original come prior to this one, people might have set those as the standard for all coming eeveelutions then. It can still happen: maybe a different artist will make something so much better in the future, that it will replace that pic as the new standard.
Think of it the following way: if you google "lapras preevolution", 80% of what you get is either a tiny lapras without shell or a tiny lapras with a simplified shell. That has been the standard for long. I myself tried to go out of those two ideas by making my own baby lapras with the shell covering half of the body entirely, kinda like a diaper or eggshell (think vullaby). But then in a thread from last week, an anon was requested to draw a baby lapras and the guy drew a mix of hermit crab and babi-fied loch ness monster that threw all I had seen before out of the water. So now if I ever come back to try and make my own baby lapras, I'll look up to that guy's rendition instead of all the previous ones. And if more artists were to see it, they'd do the same: it'd become the new standard for what "lapras preevolution" is.