As quality control is more relaxed, there’s fewer safeguards against potentially bad code (bugs or harmful stuff, intentional or non-intentional).

When there was a bit of friction between kbin and mbin, this was the starting point: kbinwas criticized for being too slow and conservative, taking ages to implement features because everything needed to be thoroughly thought through and it’s just one man doing that. Meanwhile mbin went pretty far out in the opposite extreme. Both found the approach of the other potentially harmful (by either discouraging contributors or by not having enough checks in place).