We are a small company. Developers might work on any side (front, back, customer, build/deploy, ops) when implementing a feature. So we don't really have a concept of full stack (vs not full-stack). The role is just "developer". For fresh developers, we start them on the front-end-only before they branch out.
We put them on front-end only because the tools we use for UI (MVU either in Elm or F# Elmish) are pretty beginner-safe. Early mistakes are normal and we are ok with them because we know we can fix them cheaply later. It also doesn't require as deep of a non-transferable investment as front end frameworks typically do.
Not entirely sure why front-end is still regarded as suitable for more juniors than seniors. In today's development landscape I think they're both equally complex. I also see a lot of developers being pushed into front-end and they end up hating web dev as a whole because of having to deal with layouts, design and browser inconsistencies, whereas on the back-end they wouldn't have to and might feel a lot more productive.
Since we have hired devs with no previous experience, and since we use MVU, front end is a very safe entrypoint to just learn to dev. The normal mistakes you make while learning are not overly penalized later... it takes some of the pressure off. Ultimately, the goal is to get our devs to have broad experience. And so far there is not enough of us to go around to specialize in only one area anyway.
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