I suspect that the vast majority of "big game" animals taken in the US are white tail deer. The .35 Whelen is unnecessarily poweerful for white tail, and with the wrong bullets (such as those designed for elk or moose) is actually less effective than smaller calibers.

Moreover, the .35 Whelen has been a factory cartridge for only 21 years and no great effort has been made to promote it. On the other hand, the .270 Winchester has been around since 1925 and has been actively promoted by both Jack O'Conner and Col. Whelen himself. It is a much more sensible "all-round" cartridge and has a great deal less recoil. One of the reasons for the failure of the .358 Winchester was that it was offered in the Featherweight version of the Model 70, and the recoil was fierce.

In 1987, when the .35 Whelen was introduced as a factory round, those hunters with enough knowledge to appreciate its advantages already had one in all probability, as in the case of the .22-.250, another Remington effort to legitimize a wildcat. I don't know this to be a fact, but I suspect that the .22-.250 has also failed to live up to expectations, as far as sales are concerned.