I’m not seeing how your complaint that there are too many ways to do things in Rails leads you to using a micro framework. Since Rails makes a bunch of choices for you ahead of time, there should be less ways to do things in Rails vs a micro framework.
I don't really have an exact example for you -- the last corporate rails codebase I touched was 2 migrating to 3/4, and the last rails guide I saw was 4 (rails is on 5 now?)...
More generally, my point was that smaller libraries have less space for multiple ways to do things/overlapping concepts. In the codebases I've worked with, I've found myself questioning whether to use one specific rails concept or the other and the resulting "right" choice seemed arbitrary -- like whether I should make a controller mixin or create a helper.
For example, if you look at a framework like sinatra, the smallest/simplest thing you use to respond to a request is just a function. How to use functions properly is pretty clear, there's not much else to debate over.
