Possible. And I can't speak for 31 in 1, but in the US, Action 52 was legally sold in stores. So why was that one OK, but the other multicarts illegal? And why is Action 52 not welcome on the main site? Again, legally sold in stores. There's also the Caltron 6 in 1, which was legally sold in stores.
To answer my own question, my guess would be the legal state of gaming at the time - a great deal of Atari games were unlicensed, hell, Intelliviosion even made an add on to play Atari 2600 games. The NES seems to be the last system where unlicensed games were able to make headway, like Tengen games and Game Genie.