you should note that there are two "kinds" of solo/mute:
1) midi tracks, as it is in sequencer, and
2) audio tracks / instruments, as you change behaviour in the sequencer via the mixer strip for a given track or in the mixer respectively.
this method is perfectly reasonable: just think of multitimbral instruments like kontakt where you can have up to 16 midi channels with different instrument patches associated but with a single audio output.
I hope this explanation helps clearing things up. however, if your concern points to a different direction, please elaborate
