Yup, and I've answered you.
Since it's one of the few energy independent item, it has a drawback heat wise compared to Supreme Cannon which isn't energy independent. From your point of view it's inefficient, but if you're versing an energy mech that manage to drain you, then Desolation happen to be way more efficient than SC.
Also, knock back isn't really a feature you absolutely want when you're already fighting at long range, at least in general.
You won't find any other reason apart from the ones I've just gave you.
I've assumed I dind't had to elaborate my answer since you said somewhere you're an engineer and you were applying chaos theory to the game; as you can see I've took my time to read your post in the first place and now I've also explained my point a lil further, hope it's better now!
OT: love Ice Bear!