It's not about being "better" it's about seeing an advantage, or not in your case
I used to have a Canon 20-35mm and it was honestly not the greatest lens ever made and although I use primes 99% of the time I can see the appeal of this high quality wide aperture zoo lens and I'm pretty sure it'll sell.
True, but 24-35 is even "narrower" in FL range than the 20-35.
Anyway, will stop making the point before a mod accuses me of trying to boost my post count unnecessarily.
I too think this will sell well, by the way.