In their (possible) defence, stepping outside the the narrow ESRI path of the way you're supposed to do things makes your life a massive pain. I used to work for a company that (among other things) developed tools for clients on top of ArcGIS Online. And I've had many calls where a client asks for a small and very reasonable change, and I embarrassingly have to explain that that is not the 'approved' way doing things in ArcGIS Online, so trying to make that change will essentially require us to rewrite a whole lot of components more or less from scratch and might no even be possible.

I've spent a large number of hours trying to fight ESRI software, lost more fights than I've won and even my victories have mostly been pyrrhic.