Haskell is not opinionated. All in all, it's probably easier (but misses much of the point of Haskell) to just write "IO" and "do/return" on every function in your program than to use IO in a disciplined way. Haskell even supports this with special do-syntax (and the fortuitously-named "return") to make monadic code look more imperative!

Paying that IO/do/return syntax tax (sin-tax? syn-tax?) is still cheaper than the signature/return boilerplate in competing compiled languages like C and Java. Haskell invites you avoud that syn-tax by writing principled IO.

One of the major complains of Haskell is that it is so expressive and powerful that there are so many incompatible ways of architecting modules. (see the incompatibilities in implementations of Monad Transformers / Effects, Lens, etc)

Rails is perhaps the original "opionated" system. https://guides.rubyonrails.org/getting_started.html