either you have no idea what you're talking about, or you just havent used decent snow tires.
now you definitely dont need snow tires, all seasons will get you there fine as long as you're not driving in deep snow or icy conditions. shit ive driven to the mountains in snow with toyo r888's on a rwd car, which is basically a racing slick with some small groves, it sucked ass but i made it.
but to say snow tires dont make that big of a difference is just plain stupid. the deep snow performance difference is HUGE, same with icy condition performance, especially if you have studs.
ive been on all kinds of snow tires and driven friends cars with all kinds of snow tires and even the worst ones ive driven on were significantly better than the best all seasons.
a good set of snow tires allows you to do everything so much better, not only can you haul sooo much more ass everywhere, your braking, cornering, and accelerating ability is pretty much multiplied. that and everything is so much more predictable and controllable.
i can get around significantly faster in a RWD car with good snows than i could in a wrx with good all seasons.
now that being said, dont just buy any old snow tires. get something good, if you are gonna put money towards snow tires, spend a little more and get the best, it will make a big difference. from everything ive driven, nokian hakkapellitta's are the best. ive driven on 4 different hakka's on 3 different cars and even compared to the second best snow tires ive driven, (tie between some kind of blizzaks on an sti and michelin x ice xi2's) there was a pretty damn big difference. especially in deep snow.
i just got hakka 2's now called nordman 4's i believe, with studs, ive had nordman 4's without studs and the studs make it drive like balls, but its fun, you can slide all over the place in the dry.