Printing money is the problem there, not interest. If you banned interest/loaning, you could still end up having inflation because government would print money (or do other things such as https://en.wikipedia.org/wiki/Coin#Debasement_and_clipping ).
It's a combination of interest as well as printing money. Interest keeps the deficit growing, forcing the government to print money. If we switch to a non-inflationary currency not at the control of a single entity, these wouldn't happen.
