Now we're just veering into semantics. Most games aren't a single pure genre aside from sports and puzzle games, they often blend multiple genres to varying degrees.
Ratchet & Clank, Jak, and Sly are adventure games, yes, but that's such a loose term that damn near every game is an adventure game to some extent. The point is, is platforming enough of a core part of their designs to label them as platformers? Do you need to master jumping, depth and distance perception, timing, and all that jazz to a certain degree to play them?
The original Ratchet & Clank is without a doubt a platformer. The Gorda City level definitely gives any Mario 64 level a run for their money (except Tick Tok Clock and Rainbow Ride), yet, it's also a shooter. Going Commando strays away from platforming and more into shooting and Up Your Arsenal is even more of a shooter.
Some games such as Ninja Gaiden don't feature enough platforming to be part of the discussion. You spend entire levels not platforming at all. Hell, the entire Hayabusa Village level, which is the second one, has almost no platforming.
I think we can allow a certain level of wiggle room for some games. There haven't been many pure platformers since the N64 days.