I recently learned that although WMTS layers are supported in the JS API, I can't use them as a basemap layer.
Is there an authoritative list of what sorts of layers and Portal/AGOL items can be used as a basemap layer?
I had hoped to use my own layers & AGS map services but now it seems like a bad idea.
The Basemap class's documentation says:
Basemaps can be created from a PortalItem, from a well known basemap ID, or can be used for creating custom basemaps. These basemaps may be created from tiled services you publish to your own server, or from tiled services published by third parties.