That’s what I would have said also a couple of weeks ago. I had to find out, it’s not true. See here
Manufacturers can (and should, because their new way of saving money on lens design is going the “lens profile”-way) share their lens profile by (my guess) putting it into the lens firmware.
Tamron, Tokina, Sigma, Voigtländer and Zeiss (and much more) have no special RAW developer apps.
All my Sigma lenses - quite a few - are already supported by using “manufacturer profile” in Capture One. Even a rather exotic Irix 11/4 is supported by a “generic” profile. I’ve really no profound knowledge about how these profiles find their way into Capture One, but apparently “it’s no rocket science” (and rockets are rather old items…) and DxO’s way is not the best to get. I was quite surprised to see these results and originally expected DxO to become the winner of the comparison.