If you’re really interested in knowing more then have a read of https://social.msdn.microsoft.com/Forums/windowsdesktop/en-US/3546c3c4-1b36-4552-85c5-1b3ba860ee84/how-many-dlls-can-be-loaded-in-a-process-using-loadlibrary-?forum=windowssdk
There’s a Gearslutz thread at https://www.gearslutz.com/board/steinberg-cubase-nuendo/1049652-plugins-refuse-load.html too.
It’s not the number of plug-ins in the session but rather the number of unique plug-ins which aren’t using the dynamically linked C runtime library and thankfully most of the major vendors have fixed the issues now.