Linux was called 'obsolete' in 1992, and now it powers servers around the world
(www.xda-developers.com)
I mean, from what we learnt on university the "messiness" of a monolithic kernel seems "wrong" and a microkernel arch seems "better design". Once you spend a couple of decades in the workforce and opening your mind... I haven't seen a single "good modular design" that doesn't suck balls, super bloated and with many performance issues just to make it "pretty".
So, while I'm not claiming it doesn't exist... I think is at the very least debatable.