In some ways this is even worse. In a non sparring art I've seen several instructers look to "evolve" the practice. Trouble is without resistant sparring, the evolution is based on theory. So it both takes you further away from the source (which let's assume was once effective) while at the same time not having the redeeming feature of being an improvement based on combat experience. So it becomes a lottery whether such "improvements" are actually martial improvements.
[Rex] Bow to your sensei! [/Rex]
This is the flip side of both coins sparring/non-sparring and I agree up to a point...The evolution of any art does not happen without without tradition and testing...
You can't discount either...
I've prevailed using Aikido in a few fights...Though I would not call it "Combat"