The limit is 10, no idea how often the resets happen. If you run out before a reset hits you can contact Runic support and they will reset it for you. I don't see how someone could burn through 10 installs in a short period unless they are the type that gets a virus every week and has to reformat their hard drive.

Yeah, the nerve of a company giving customers a choice where to buy their product.

They made their own online infrastructure for the game that you use to play online weather you bought the steam version or not. If someone wants to buy a version that doesn't need steam management on top of that they are doing nothing wrong. You have stated support before of getting games elsewhere besides steam that needed extra accounts for online features.