Phoenix is using Plug. If you’re okay with hooking up everything yourself, there’s no problem just going with Plug, and Cowboy/Bandit directly.
I would not do it, and most people would not do it too probably, because it may prove to be extra work nobody wants to do, and end result being inferior to what Phoenix provides out of the box anyway, but people have free will and if - for example - it’s a learning exercise - go for it!
