How come that the Jupyter variable inspector is only available for local kernels?

I am currently evaluating a switch to Pycharm for working with Jupyter notebooks, my daily environment. I have debugging all morning why Pycharm's Jupyter variable explorer is only showing "Variables not available" when running Jupyter on a remote server, suspecting the cause to be similar to https://youtrack.jetbrains.com/issue/PY-43337.

Now I find in the documentation (https://www.jetbrains.com/help/pycharm/running-jupyter-notebook-cells.html#variables ) that "This functionality is available only for local Jupyter server kernels.". Why is this so, when Visual Studio Code can brilliantly show my Jupyter variables when running remotely?