Replying to Do ski socks actually matter

Up until this season I always used regular socks, but I got new boots and the bootfitter said I had to wear ski socks or they wouldn't work. I haven't really noticed a difference but it's hard to tell because they're different boots. My problem is that with my old boots and normal socks, I never got cold, but now my feet go numb super fast even if it's pretty warm out. Do you think going back to normal socks would help this or not? Also do ski socks really help your skiing or are they just a gimmick?