HTS has cut off ties with ALQaeda and IS since almost 10 years.
B) they released all prisoners now. And at least some of them were part of ISIS.
The point is, that no matter what they did, they are all free now.
If their numbers are so small, why was the IS a global problem then, a couple of years ago?
While the US spend lots of effort on hunting them?
Keeping the flames high, to play firemen?
I don't think that there was a need of more flames, for that theory to be plausible. Occasionally some western weapons likely did found their ways towards IS as well, but they rather captured the bulk of it. Or do you have other sources?