I remember in the old days, shinyUI() and shinyServer() were required when building apps.
I've stopped using them long ago, but I still see many people use them.
Looking at the actual function bodies, it looks like all they do is set the .globals$ui/server variable. When looking at the shiny codebase, I only found one place where that's used: https://github.com/rstudio/shiny/blob/aff3ac0bb3b471a2e5a73d0423ee7ee3d896604c/R/app.R#L154-L161
I didn't understand why it's used there, but I was wondering if there is ever a reason to use them?