If you don't think a disc and bars help out, you've obviously never ridden one.

I dropped over 50 seconds with bars + Disc + Trispoke on a 10 mile TT, still completely undialed in (as in my aero position was pretty ****ty), even after not training as hard (Season ended before I could bust out the big guns), versus track drops and 32 spoke Deep V's.

My Zipp 900 weighs less than my Mavic Aksium Equipe spoked wheel, but then again, it's a very expensive disc.

What's worth noting is Zipp's construction technique of the disc has not changed much in the last 20 years. The hub and rim edge are better but it's still a sandwich foam core carbon wheel.

The newer lenticular wheels from zipp (and HED as well) are actually spoked wheels with a very light cover on them, which is why they are not track compatible, as they're not very stiff (They're more marketed towards triathletes/pro skinny TT racers).