I don’t know how you all came to the conclusion of such a limitaiton, but it never existed. I’ve always used several dozen markers in my projects since at least Cubase VST5/32 released in 2000 or 2001. There used to even be a function for assigning each marker to a note on the MIDI master keyboard, allowing up to 128 markers. I tested this function at the time, but didn’t keep it because I had no use for it. I was just as quick with the keyboard shortcuts for jumping from the previous marker to the next.
I’m pasting here a snapshot I took while testing one of my projects on Cubase Pro 13 to prove that you can go well beyond 10 markers per project.