i think burst itself is fine as long as the champion bursting has reasonable counterplay
you can see an akali coming at you, CC her, drop a pink ward, and kill her
you can see a riven coming at you, CC her, and kill her from range
you can see a talon coming at you, drop a pink or run away when he ults, CC him and kill him
but then there's syndra who can 1 shot you from the fog of war simply by landing a single skill shot
and there's zed who can blink-gapclose to you, which conveniently allows him to dodge most forms of CC, and then burst you 100-0 and escape back to where he blinked in instantly (also dodging many forms of CC)
and then there's fizz who can dodge all of your CC with a low cooldown skill, clear an entire minion wave or do AOE damage to your team when he lands, Q to safety and zhonyas and then his troll poll is up again by the time zhonyas is over.
so it really just depends on the champion and their kit. Riots already removed all the silences from assassins, which is a great move imo. I think they need to go a bit farther and give more options for counterplay to several (namely the 3 listed above).
just yesterday i was playing Ahri, my favorite midlaner. I was against an Akali player who liked to roam a lot so i took to sitting in bushes waiting for her to return to lane. After I finished my DFG I was able to 1 shot akali from the bush simply by landing my charm and executing my combo properly. There was zero opportunity for counterplay on her end other than dodging the charm.
Now one could argue that she shouldn't be facechecking bushes when there's a DFG ahri around, and that she should ward better amongst other things. So sure, there are some things that could be done to 'counter' this 1 shot combo, but the fact remains that even if she takes all those measures i can still hit my charm if i aim it well, and if that charm lands she's 100-0 dead. That's probably an issue.