Because Patchwork came out after MB-7 and is a whole other animal.
Virtual patchbay is what I would say and host plugins until your computer crashes as you can use hundreds if not more Patchworks before it says stop, we have routed so many plugins i thought the macs we use would puke but everything just works
MB-7 only host so many per Cat and you can't do routing as you can in PT so Patchwork is a better option if you wanna make your own plugin chains.
MB-7 works great if you need to host a VI here or there though,
Best way is to read up on bluecats website as they have videos too.
Best
Christopher