That's fair, the interviewers did put unreasonable restrictions on the challenge that forced the overly clever solution. It was my kneejerk response from personal experience seeing candidates come up with overly clever solutions even to simple job challenges.

But even still, let's assume there is a problem out there with unreasonable requirements. And let's say an engineer architects a solution to that problem in 100% TS. How's that going to solve anything? When the inputs and outputs are types... how do you interface with such a solution? You can't because types only exist at compile time so there's no way to dynamically send in inputs and retrieve outputs (at least not without even more hacks/cleverness).