> Adding something like this were people are inventing complexity in the language itself out of boredom is a recipe for disaster

Not really. This is a fun project to show what an effects system would look like. The consequences of this are pretty much strictly positive.

> and is much worse than the terrible things than can happen in C.

No. "Ugly code no one will use but that demonstrates a concept" is definitely not worse than "attacker has full control over the computer".