The reasons IMHO are follows

1 The 358 win does almost the same as a 35 Whelan with 225 gr bullets in a short action or a lever action. Even that never caught on much. Ruger & Browning still sell a few 358 Wins but not many 35 Whelens.
2 The 250 gr bullet is the largest commonly available in 35 cal. Occasionally one sees 275 grs. The barrel twist is too slow for larger bullets.
3 Compare this with the 9.3X62 - this cartridge is an "improved" Whelen that gives 175 fps more velocity with 250 gr bullets. It shoots 286 gr bullets easily. It can even shoot the 320g Woodleighs at 2100 fps.
4 Europe & Africa have used the 9.3X62 for over 100 years & it is still very popular.
5 The 338 Win Mag has probably taken some of the interest away.