Sorry but I'm not quite sure what you are disagreeing with, Immersion.
Your basic compressor (not multiband) is for controlling amplitude without respect to frequency. So it can smooth a mix that has harsh peaks by knocking those peaks down a bit ... wherever those peaks are throughout the frequency spectrum. So yes, it can cut harsh edges or volume spikes in this way.
An EQ is frequency specific. You can also lower volume peaks with it, but always over a particular frequency range. But of course you can also use it to lower particular frequencies that are already low in a mix, which a basic compressor does not do.
What's important, for me, is not so much the individual compressors used but the individual tracks you have to master. Some tracks can be in bad need of compression because of wayward dynamics that need taming, and this is often a matter of inadequate mixing (and recording) of the track in the first place. But I'd probably still use EQ along with the compressor. Or maybe use a multiband compressor.
A good mix may need no compression, but it may still need some massaging to bring it in line with other tracks on an album ... which is what mastering is all about.
Compressors are great for controlling dynamics in a live recording environment (singer, guitar, drum mics, etc).
The compressor consist of many different sound shaping elements, such as filters etc, all together makes an complete compressor.
The Sonalksis compressor does definitely sound smooth and does not destroy the sound in an non-beautiful way.
For me the compressor is not only a mastering tool, but a mixing tool, since it makes inaudible low level information audible in the mix.
Sure you could do this with EQ also, but in that way you might loose even more audio information in the mix.
And ambient music is not for instance classical music, where a total dynamic range is needed, ambient is walls of sounds... However
I think you should use booth tools, so meaningless discussion for me.....there is no wrong way to create your sounds...as long as it sounds good to your ears.