At lvl 6:
Ignite does 205 damage.
Electrocute does at least 110 damage (more depending on ad)
315 damage right there.
Typical mage max hp at lvl 6:
36% of velkoz's max hp is gone to Ignite and Electrocute. Gets worse for adcs and supports.
Now factor in minor runes, hextech revolver or serrated dirk passives, bonus ad from runes.
Over 400 free damage at least approaching nearly 50% of champion max hp at lvl 6. and then the natural burst assassins have...
It becomes pretty clear that even a blind amputee monkey is going to get some 100-0 kills.
What I think should happen:
Decrease Electrocute damage but also decrease the cooldown.
Decrease Ignite cooldown significantly, but also reduce the damage significantly.
Slightly reduce revolver/dirk damage
This reduces their max burst, but decreases the time between their plays. So you'll see Assassins going for plays more often, but those plays should individually be less impactful.
So, if both players have their summoners up, the player with defensive summoners will be unlikely to die. However, there is a huge window of time where one player has Ignite up and the other does not even have barrier/heal ready.