How much does the ski you use actually truly matter?

The other day I went skiing for four days through deep powder and trees with mates who not only didn't have powder skis, but were on shitty stiff 15-year old rental skis with 70-cm waists made for beginners. They aren't super advanced skiers, mid-intermediates maybe, but were able to keep up no problem, other than having a few times where their skis released due to low DIN settings.

This made me wonder how much gear actually truly makes a difference. I know this sub and myself included can get obsessive over picking the perfect ski, but is this mostly just over-engineering for minute differences that don't matter that much? Other than the big things like ski length and weight, do all the little things about shape and sidecut we optimize for actually make a huge difference to our enjoyment on the mountain, or does this really only really make a difference for pro-level athletes?

I just think of my dad's generation in the old country, ripping it on homemade wood planks and bindings made of whatever they can find, and having a great time anyway.