I had the same issue with 22, it wasn't pretty clear to me. But once I googled "Weighted average" I was like "Ohhhh that's what they want"...

Many times, one would think of splitting the code in a certain way so that it can be reused or be generic enough so that if more applications/consumers need to use it in the future, it will be ready for it.

I don't think this is exactly how the principle should be interpreted.
I find myself utilising it a lot when looking into abstractions or when creating services.