Hmm, that's pretty much me when I have all my effects switched out.
But I think the question wasn't about incidental compression but about deliberately introducing it; there's a big difference between the compression inherent in the system and controllable compression you add on purpose.
A bit like saying don't use filters on your camera, as without them it won't replicate colours perfectly anyway.
If you have, for example, a valve amp driven hard, then you might decide there's no benefit. For me with a solid state combo that only lights the light in Can't Stop it makes a very noticeable difference to add compression.
My old Laney head has a cheap IC in it (NE571) that I always assumed was wired up just as a 2:1 range compressor.
Having compared the datasheet and the schematic it's not conventional as the reference voltage is derived from the power amp output, a bit hard to decide exactly what is happening but I think it combines range compression and limiting (by increasing the compression as the power amp output rises). They only use half the IC.
If anyone can figure it out from the attached....
ProBassPreamp.pdf
NE570 compander.pdf