[ldar15]

it was an engineering generalization that made certain features easier to develop

The rallying call of poor programmers everywhere.

Its not about ease of engineering. Its about consequences. The game designers wanted an invisibility card. There were two ways to program it, one easy and one hard (you're talking to HN, so I imagine a lot of people here can think of ways to implement a system with all of the constraints you describe).

They chose the easy one. Either because they couldn't think of the hard one, they didn't think the easy one would have consequences, or they were overruled. The OP's surprise seems to suggest a lack of forethought.