What you see is the result of the fact Haskell gives you expressiveness to build anything from a shed to a bridge or a sky scraper and people who adopt Haskell are curious by nature and thus go as deep as possible and try to build a small house taking air currents and earthquakes into the equation.

Servant is very complex by itself. It's hard to tell at what scale it pays off. But it gives you more safety than other solutions.

I would love to have the OP on my team, because they have the ambition to build reliable software and I can compromise with them. It's hard to compromise the other way around.