At any rate, my actual opinion is that disc is better. Is it required? Probably not in most areas, certainly not around here. I can get up and down any of our mountains on rim brake just fine.
The ease of maintenance thing is certainly an objective benefit in favor of rim brake, but many modern riders or MTBers are not really fazed too much by disc, so its not a huge disadvantage for lots of people. I haven't actually check components weights, but I can't imagine it's actually impactful. I'm a racer and outside of TT I don't really pay a ton of attention to my equipment TBH, not nearly as much as many here.
__________________
"Your beauty is an aeroplane;
so high, my heart cannot bear the strain." -A.C. Jobim, Triste