Only because odd components aren't marketable. There used to be 4-terminal MOSFETs, they weren't sold after ICs became normal. Never heard of a multi emitter transistor being sold discretely but it's possible.
https://hackaday.com/2011/08/05/building-a-computer-out-of-5...
exactly :)
BF901 FTW.
Is that what you had in mind?