The fact that the product is an astrology product will also impose some kind of filter on the people who choose to work there.
Maybe that's why they could only hire Haskell devs.
A cynicism filter?
I agree. Two out of the three things listed here you can easily do with Typescript. But good luck getting web developers to not just use strings for everything.
Thankfully, with latest TS updates, all of those strings and their combinations can be safely typed, too.