I disagree mostly because, comparative to what you said, there's far more difference in what you've listed than the diver staples of point-and-click gapcloser, singular CC ability (often a knock-up) and aa modifier or spell.
As an example, let's see the "defensive" abilities for some ADCs:
Her net, which knocks her enemy back, slows the target and procs a headshot.
Stand aside, which knocks enemies to the side in front of him.
Smokescreen, which limits vision radius afor enemies in the bubble.
Spellshield, which blocks the next spell and restores mana.
An instant blink in a direction that teleports Ezreal.
and so on. Despite all of them possessing a "defensive" ability, each one has some unique hook or variation. As another comparison, let's look at mage ults:
knocks back people in a line to his outer rim.
creates an impassable wall that hits people back.
stuns everyone who is facing her.
"DO OVER"
AoE channel that hits a bunch of targets near her.
I mean I could list more and I'm certainly missing some mages who -do- fit your category, but suffice to say there's quite a bit of variation, even if mages do occupy and fit similar roles.
Now let's look at diver ults, as per the example:
Right-clicks someone, ignoring effects and CCIng the target with an unbreakable teather.
Right-clicks someone, diving onto them and dealing heavy attack damage while creating a wall.
Right clicks someone, creating impassable walls around the target and dealing bonus damage.
Leaps in a direction, dragging enemies with her and empowering her abilities for a short time.
Right-clicks someone, knocking them back and dealing pretty heavy damage.
Even if these abilities -do- have some unique properties (and I'm missing certain divers with more varied ults), they often fall into the exact same circumstance with little variation in how they function or what they do. Divers don't have nearly the same unique hooks and can be boiled down far more easily than something like tanks or ADCs who are more "general" in their kit designs.