I sometimes wonder how my career (and life) would've differed if 11 years ago, I had chosen to learn rails instead of laravel because of familiarity with php via Wordpress. From there it went on to C# (windows), JS (frontend), scala/go/node.js backend + JS front end. Lots of JS.

Here being Japan, there were a lot of opportunities to pick up ruby/rails along the way but I stuck on the JS trajectory partially because I didn't want to 'start over' with rails _now_. There were only a few times when not knowing ruby/rails meant I was limited to specific tasks so it was never really career limiting. It did mean that I actively avoided working in ruby shops, for better or worse.

If I had picked rails instead then, would I have transitioned into more of a backend engineer with some frontend duties instead of the reverse?

Not that it matters, but there definitely is a tendency in our industry to 'look down' on frontenders as not real engineers and thus not consider them for leadership positions.