Nope, this happens when UB levels quickly and spends tons at the artifact shop, AI Reg abuses this to.  Then again every once in a while I can do a similar thing with Rook if I can get that insane cash flow. (1500000+ damage in one game, several thousand grunts, a few dozen kills)

It's not really an issue with demigod balance as much as it is one guy buying out the artifact shop.

EDIT: forgot to mention you can do this with TB too

I've only really done it with Rook, basically Allfather Ring, Deathbringer, Ashkalon (?), Hauberk of Ages (?), Giant's Belt (?), and the spear which gives you a buttload of mana, plus furious blade as my favor item.  Rook became faster than UB with 10k HP, 6k mana, insane hp regen and lifesteal, 600-800 dmg per cleaving hit, with a chance to do 1700 cleaving damage, and with the furious blade stacking on the Ash, his attack speed became roughly a quarter of a second.

Granted this took over an hour to get enough gold, but Rook became unkillable and could kill an enemy Demigod in a few seconds.