I hope this is not considered off-topic, but unless I misunderstand category killer (which is totally possible

, have always felt confused by how term was being used), it seems to me many of the submissions here are not really category killer?
To me category killer means that you have the one name that many people would naturally search for. So for example hotels.com, flights.com, etc. are clearly category killer.
Now category killers can be more specific, as long as they define a category that people would search for, in my way of thinking. So FertilityClinics, SleepAids, EnvironmentalConsulting are also probably category killer I think.
To me once something else is tacked on they are no longer category killer. Like BestSleepAids, while possibly a really good domain name, is not, to me, category killer. Same for LAFertilityClinics (again a great name, but to me not CK, or am I wrong and it is?).
The other thing unclear in my mind is when something does define a category, but it is very narrow. Let's say a name like ScienceActivityParties is in a sense something someone might search naturally for and it would be the obvious term if they wanted a service or ideas for a science-themed party. But to me that is not category killer since ScienceActivityIdeas or ScienceActivityPartyService etc. are almost in same class. If there are a bunch of nearly equally good something is not category killer to me.
What about PinkStandupPaddleboard.com Yes, if someone is searching only for pink paddleboards it defines the class (or maybe plural would better) but to me that is too narrow. But maybe it is indeed a category killer?
So am I off in my thinking?
As I define it I think (in .com) I don''t have any category killer names. The closest I might have is MedicalCRISPR.com. If someone was looking for medical clinics that use CRISPR genetic editing to treat health conditions I would argue that Medical CRISPR is as category defining as perhaps possible. But I myself do not treat it as category killer, even if we were 5 years in future and CRISPR had moved from research labs to clinical treatment.
Bob