Just a comment on the “Focus on Similar” point. Indeed, it’s recognised that in many cases (not all), the “Focus on Similar” button returns too broad a selection, and it has been this way for a very long time.
There could be any number of reasons for this, ranging from “it’s low down on the priority list of things to do” to “it’s a hard nut to crack”.
Given that it probably draws upon Genre metadata, some insight into how complex the whole topic of genres is can be seen from this thread, which was in fact kicked off by Brian…