A loophole lets you evade the purpose of a rule or law. It’s a sign of a poorly crafted rule which lets you get away with exactly what the rule was meant to prohibit. A lot of what we think of as loopholes in the rules of NHL roster making, particularly around injury reserve, are not that at all; rather, they’re unintended consequences of a system that is designed to achieve specific goals.
This is only the most recent injured reserve roster shenanigan around these parts, and no, it’s not unique to the Maple Leafs. Toronto is just being much more blatant than other teams have been.