You can submit feedback requests on https://feedback.azure.com/d365community/forum/04fe6ee0-3b25-ec11-b6e6-000d3a4f0da0. When you do this, make sure that you explain your business clearly, because that is something that Microsoft pays attention to.
I think you absolutely have a valid use case. But I am not really holding my breath that Microsoft will address this, because I can see the challenge. As Bruce says, SQL Server was not designed for this case. Rather, SQL Server has been designed to be used within an Enterprise where applications share the load in solidarity. That is, one process can produce a lot of physical reads that drags a lot of data into the cache - which then other processes can benefit from.
I brought this up with some MVP colleagues, and one mentioned "SQL insights", that I don't know what it is, but he reported he had a customer using it in way you are looking into. Other suggestions included using extended events to monitor calls and using SqlConnection.RetrieveStatistics. But there was also the obvious comment that it's a lot simpler with one database per tenant. And if you use stored procedures, you could add your own accounting to those.