A few things to chew on:
The Frost Giant does indeed re-use the Marvel Icons Thor figure released a couple years back as a base; all of the 4 giant figures in this Walmart exclusive line re-used existing Icon bodies. You're not going to find a lot of new tooling on retail exclusives, although Hasbro will do some new parts, unlike Mattel.
The Frost Giant likely does have a higher production run than Tytus, but also possibly NOT by the huge margin alluded to in some posts above. Retailer exclusives are still limited runs, and, as with most lines these days, only some Walmarts carry Marvel Universe, which likely reduces the numbers even more. Only one of three Wallys in my area carry it.
The Frost Giant actually does go well with Mattel product in one way: Hasbro's Icons bodies usually have a very sticky hip joint that doesn't want to move easily.
Also, the information Mattel gave us about what could and couldn't be done with the 12" rotocast figures is highly suspect all around. Please recall that they said doing a ball joint with a rotocast figure was not possible. Problem is, back around 2004, two 12" rotocast figures were made with ball jointed shoulders in a line called Masters of the Universe, manufactured by a little known company called Mattel. Given that as a starting point, I don't exactly accept any of what followed at face value.