I completely understand your point of view.
Synths have never bothered me, EXCEPT when they encroach a little too much on the rest of the instruments. So first of all, Hard FM is something I've never appreciated, and it makes me run the 110-meter hurdles in less than a tenth of a second.
But when it serves the music, to add an atmosphere, a mood, but behind it, the music blows its energy through the guitars or the drums, I'm fine with that.
I can't imagine Emperor's In the Nightside Eclipse without this gloomy, omnipresent atmosphere. Just the guitars and the drums, if I take up your comparison with coffee, it would be like being served a cup of coffee, but without anything in it. For me, of course.
I love Bal-Sagoth, for example, but I have to admit that after listening to one album, or even 2, I just can't take it anymore. The keyboards are too prominent.