Let me be clear; if anyone here plays an instrument, you know how important Adam's bass lines are. Ever play ISHFWILF note for note on guitar? I have. Sound like anything special? Hell no. Add the bassline, boom, instant tune.
The same can be said for MOST u2 songs. The list could go on and on. But, the comment was "Eno and Lanois are as important musically as Adam" and I have to agree with that as far as album production goes.
So, Adam is a special part of the band.
HOWEVER:
The MOOD and atmosphere, not to mention the direction in songwriting, part playing, and ESPECIALLY the production, would be nowhere without Eno/Lanois. Which I find myself biting my teeth saying because I hate Eno or Lanois' music solo.