Because it is heavily inspired by Rails, bringing the same problems but taking it to a whole new level which kinda kills most of benefits of Rails.
You still have a tons of code under the hood and lots of opinions (like Rails) but with a bunch of over-engineered stuff on top (unlike Rails). When working with Rails, the amount of code/patterns I need to learn is a trade-off I'm willing to take because there's a bunch of patterns that you pretty much don't need much more flexibility than it offers already (controllers/routes/views-helpers for example), ActiveRecord on the other end, sometimes is a pain in the ass. Rails is already border-line too much shit to just receive a request and concatenate a response but it's "ok" since it's fullstack (connecting to a database, serializing objects, adding headers, localization and etc is still something not so trivial).
Rails was born questioning the massive complexity of Java frameworks for webdev. And I still think Rails does too much stuff (like what's wrong with