Multi-band compressors are HIGHLY looked down upon everywhere outside electronic music. One of the main reasons is that, between every single band, there is a section that is not affected, and, as you can imagine, can mess with tones for real instruments as they have stricter guidelines (industry standards) for mixing than compared to electronic music. Having that said, it won't really affect the tones of a set of sawtooth chords, as you can imagine.
But overall, yes, they are mainly used for digital mastering. I personally don't use multiband compressors anymore to master because I don't particularly like the way they sound. I tend to finely tune every little cycle of my mix and keep the mastering extremely simple--a pre-EQ, maybe a harmonic exciter, a simple vintage compressor and limiter, and done. Multiband compressors can also make your mix much louder than a normal compressor, which is another factor of why it's so popular in the electronic music world.