Well, counting the "hits" is the way WoD does it.It's not. I thought the definition of a dice pool system was counting the number of "hits" and not adding up the numbers and comparing that to a target number - which is what GURPS does. From what I can see posters are mixing things up.
There is also the bizarre way that Whispering Vault (and some kind of WWII supers game that I forget the title of) did it (which involved finding the total of the most matching dice vs difficulty, IIRC), Cortex Plus (Marvel Heroic, Firefly, Smallville, and Leverage) builds a dice pool from the character's various modes, features, distinctions, etc. then you take the sum of the best two, and the largest uncounted is your "effect" die. (So, for a given roll, you might be rolling 1d10 & 2d8 & 1d6). There's a fringe, but very interesting game called Schema, for which you roll a number of d6/DFs and use the results to either buy off bad results or buy good results. Similarly the new Genesys system (a la Edge of the Empire) has its own wonky dice that you build a pool out of.
To me, a "dice pool" system is a system where you "build a pool" from your various character attributes to make the roll. Whether those dice are all the same size or not doesn't matter, nor does whether or not you sum them or resolve it in some other way. The GURPS type is questionable for me, and I would tend not to include it, because you're always rolling the same 3d6 and your skills are reflected in a modifier, not the number or size of dice included.