This is interesting, and I think it's perfect for my furry artlang :
The justification would that animals don't have the same number of digits so they choose some common ground... Which doesn't necessarilly help Equus or even-toed ungulates counting on their finger, but, well you still have to have a practical base, so... at least lot of species have more than 3 finger on one member. All the practicale stuff about seximal is just a bonus.
One more practicale aspect for me is that I have less work to do to figure out words for numbers.
I wonder if there is a place I could have my artlang reviewed...
I mean I would feel awkward crashing a conlang forum and say "Hey, here my stuff, tell me it's the best!" (well it wouldn't go like that but that's how I would feel... )
Now I can count in my art-lang that still doesn't even have a name. \o/
#conlang