and
have their dashes, but their mobility is reduced by other factors in the kit.
is bound to her tentacles, so even if she can chase some of the least mobile champions down, that's not really a viable move for her, and she needs said champion to walk up 225 units to her to even begin that chase.
not only severely slows himself, but his three other abilities either have cast times to slow him down further, or just plain make him stand still (R recast). He also has 330 base movespeed to begin with.
You can't really compare any jugg to a champion with high base MS, can double-dash for 600 units total without any requirements (like enemy target, or a cast time), and gets 240 bonus movespeed on top of that. He has some cast times in his kit, but that's all, and not only those cast times aren't that high, he is even allowed to dash during them. It's not even comparable with punishment that actual juggs get if they "break the rules" by having a dash.
Instead of counting cd on dashes, it's easier to think in terms of closing or creating a gap.
Aatrox can easily (though not instantly) close or create gaps of 600 units, or a bit more then 700 if he ults. Even without ult, it's enough to prevent every ADC from attacking him for free - a good rule of thumb to distinguish between a jugg and a diver.
Illaoi can only close 225, and can't really create one.
Urgot can close or create about just below 400, depending how much ground enemy covers during windup.
There really is no comparison.