I think you need a bit more clarity and thinking on this.
You do already get a 1 to 1 track/channels with any instrument that is not multitimbral.
S1 is actually designed and give you better performance when you do use it in that fashion.
In other words, if you are used to having 5 Instruments in Kontakt, for example, trying adding 5 instances of Kontakt with one instrument per. It actually works better that way. Mutes are less confusing.
Anyway, I understand your premise.
I think you meant to say Multi out instruments optionally get added with matching multiple ins?