This mostly makes it impossible for users (and myself while designing the report) to alter anything. Resizing column widths is no longer possible, which eliminates the need for the scroll bar altogether.
With this approach I have been unsuccessful in getting the scroll bar to show, neither in Chart, nor in Container
Just discovered something (while investigating the web for the issue some more):
I have removed the description field from the dimensions and added it as an expression using Only() function. This gives me the horizontal scroll bar in the Straight Table Chart itself, no need for Container anymore.
It has an insane Set Analysis formula behind it to make sure it only shows the lines that actually also have metric data, but it works for my purpose.
Still a nuisance to have to work in such a complicated way, especially if the different metrics have very different set analysis, finding the one that works for the description could be a challenge.