That's just simply not true though...

Do users explicitly care about how many milliseconds somethings takes? No definitely not

Do they care if the application feels slow ? Yes absolutely Do faster experiences subconsciously feel better ? Yes Does that subconscious feeling, impact metrics like sales or conversion ? Yes it does

All the (dozens and hundreds) milliseconds add up and the sum of it is perceived easily

People pretty regularly say they buy iPhones because of the very smooth UI (performance), that they buy an ARM Mac because it's so much faster, etc. Google won partly because it was so fast.

So people do explicitly justify usage decisions with performance, all the time. Agreed that overall features win out but it's often the case that multiple products end up with broadly comparable sets of features and struggle to gain a persistent advantage there. Once you reach that point, perf can be a competitive advantage.