The solution to assassins isn't beefier tanks, its supports that can protect.

Give supports more tools to protect ADC's / APC's such as granted spell shields on an active item with a cooldown. There are items that reduce damage taken / transfer. But simple solution are to buff the real support classes, You know the guys with CC and utility that don't have crazy damage you bring just to one shot a carry.

All these support mages are flooding the bot lane and really aren't helping the problem. The problem isn't damage creep, its the ability to negate it without just killing the other person.