Wouldn't the whole situation be resolved if roles were more clearly defined by abilities rather than items? For example, a champion who is meant to be a tank would possess abilities which enhances his ability to tank.
Here is a shoddy demonstration of a random champion creation to illustrate what I mean:
Champion Name: Tankerman
Abilities:
Q: Stop Damage!
Tankerman puts up his hands and demands with all his will power to stop all incoming damage. Activating this skill reduces all incoming damage by 20/25/30/35/40% for 0.5/0.75/1/1.25/1.5 seconds.
W: Protect Life!
Tankerman shouts at the top of his lungs to command his will power to protect the target with a shield! Activating skill will grant a shield on target protecting for 50/80/110/140/170 + 10/15/20/25/30% of their max HP for 2 seconds. This skill can be activated while CCed but will be self-casted.
E: You not hurt!
Tankerman commands the target to not hurt anyone! Activating skill will reduces the target's damage dealt by 5/8/11/14/17% and heal the victim for the same amount based on damage dealt after reductions!
R: Me Shield Friends!
Tankerman commands the entirety of his will power to form a powerful aoe shield that decays over time. Activating grants a shield that blocks for 200/400/600 + 20/40/60% of Tankerman's current health for 5 seconds. It decays at a rate of 10/50/100 damage per second.
Passive Skill: Tankerman's auto attacks invigorates him with hope that he can win! Each successive auto attack grants a stack of invigoration which grants 10 + 1/2/3/4% (upgrades each time Tankerman upgrades his ultimate) of his max health as bonus physical damage. Each stack lasts for 7 seconds and it can stack up to 10 times. Successful interactions with his abilities such as reducing incoming damage with his Q, blocking damage with his W or reducing outgoing damage with his E or blocking damage with his Ultimate will grant 2 stacks of invigoration.
Of course, items would need to be revamped as well to ensure that this change has meaning since roles are more clearly defined by items than they are by abilities (eg. you can build tank annie and be the front line if you are support annie).