Almost every manufacturer makes their skis by hand, on some level. They don't just dump "ski ingredients" into some kinda machine a ski pops out. And even the "truly handmade" skis need some machining process, like a press. There are hand processes and machine processes required to make every ski.
The issue really comes down to the selecting the best materials, processes, and engineering. Just because some guy made a ski in his garage doesn't make it awesome. Does it make it unique? Yes. But not every unique thing is a good thing. I've seen some utterly horrible handmade "boutique" skis (just flip a ski on its side and look down the edge from tip to tail and you'll see what I mean- if it's all wavy and shit it will suck. a lot.) and I've seen some amazing skis from "big manufacturers". It's why a lot of smaller companies (like Armada) have a larger company
(like Atomic) press their skis. Ski companies that have been pressing
skis since 1950 usually know a thing or two about how to make a ski. That said I've seen awesome boutique skis and shitty skis from big manufacturers. Again, it always comes down to material selection, processes, and engineering. Not all wood cores are created equal, not all top sheets are created equal, etc.