When I add the NASA GIBS EPSG:3857 GetCapabilities endpoint to ArcGIS Online, it correctly parses it and I am able to add a layer. However, ArcGIS Online is not parsing the GC to support the 'time' Dimension. A sample Dimension element is seen here:
When I add a parameter via the interface, it tacks it on as a query parameter, and does not follow the ResourceURL found in the Capabilities document. A sample is seen here:
Note that this usage of 'time' is compliant with Annex C of the WMS 1.3.0 specification, specifically using the "min/max/resolution" nomenclature for possible.
So my question/requests is: When will ArcGIS support custom Dimensions specified in a Capabilities document, especially 'time'?
As you found, only the default value is supported in ArcGIS Online when adding the capabilities url. You can however still add any time value the WMTS supports by using an alternate workflow: When adding a layer from the web, instead of selecting the WMTS option, select the Tile layer option (Screenshot below). With the tile layer option, you can provide the specific time you want to see when inputting the url.
Here are a couple examples (same structure as the parameterized url you posted from the capabilities doc):
As for native support of dimensions (time and other), no estimate on when support might be added (though I saw you've submitted on the ideas site for future consideration).
Meh. If I go that route, there isn't a way to change the date without re-adding a whole new layer. So, sure, this is functional. But that's a fairly low bar. Hopefully Esri will get to this eventually.
FYI, you've got the row/col switched. It should be this: