Assassins: Weak early, strong late?

At least shouldn't assassins be like that? Most of them are strong early lane bullies that can chunk a quarter of your health with a single poke ability. Add over that their tower-diving capabilities and at lvl 6 most of them can just dive you and 100-0 you. The only reason they are not OP is because they kinda suck lategame, a single exhaust or CC utterly destroys them in a teamfight.

Shouldn't it be the other way around? Give them lower base damage, but stronger scaling. That way they have to work more to get kills early, and emphasis on finding low-health targets and dive them, promoting intelligent gameplay. And stronger scaling would allow them to catch up and/or scale into lategame so they remain relevant.

It just seems idiotic that most assassins can just towerdive and one-shot squishies at lvl 6 with little effort, but their lack of late-game relevency pushes them to finish the game quickly or become deadweight.

Currently assassins are just really frustrating early game, with a lack of counterplay, but at the same time i feel sad for them whenever one gets disgustingly fed early, only to be unable to snatch a single kill later if the game lasts long enough.