The first billion credit hosted games I remember hearing about were on xbox.
As far as PC goes, I suppose I don't endorse cheating or modding for public games. If someone wants to screw around with their own account or mod the game to play with friends it doesn't affect me or others.
Also with regards to the increased payouts, from a technical standpoint I don't see why anybody does that at all on PC. If you want more credits you can potentially just give yourself more credits. No need to give everybody in public games more credits just to troll them into worrying about ban waves (even if they don't happen now).
That said, I recall people getting millions of credits when the ban waves were still on who self reported and for some reason BW never adjusted their credit totals. Of course having the credits and spending the credits were a separate issue and it seemed like they were more aggressive at targeting people who spent millions of credits in the store in one day.
If you want to split hairs about all of this, I find 66666 glitching and modding stats or weapons for player advantage more egregious than credit or item glitching, and then you have objective RNG modding or modding wave composition for something like horde mode or even modding the game for testing mechanics which are more like misdemeanors. Technically it was all taboo but at the one end you aren't really just creating win buttons for yourself.