You know, I tought about what I just said while looking at some of my furry work, and... I think it's linked to the style, finally xD
I tend to make necks really short in fact. Really small. But yeah, you can find many different ways to draw ponies on the internet. Anthro, cartoon, realistic, whatever you want, there's a lot of possible interpretations.
So I guess the fact I don't like long necks might just be my opinion and my personal way to look at things. It's not an technical "error", I just prefer it like that. ^^ So I'm also going to withdraw what I said some minutes ago: Long necks works too. Even if I don't like it
But yes, I agree by the fact real ponies in real life do have long necks, eheh. ^^"