I saw this post some days ago https://www.reddit.com/r/leagueoflegends/comments/9z7f8r/the_state_of_adcsmarksman_soloq_change_my_mind/
Im also diamond adc averaging d3 rank, i played this game since season 3 (2013) I never felt this useless. I would be just happy if they reverted IE so i can deal 50% increased damage on crits. Make that change and then see how adcs are, they only viable adc imo rn is kaisa and mages. But that doesnt matter. Adcs are useless and needs buffs asap.
As for tanks i really think tanks also need a buff since they are also a really useless role atm.. Except sion cuz that champion is completely broken. But other tanks are unplayble partly because adcs are useless. Its kinda sad how sometimes some roles are unplayable, atm it is adc and tanks. A friend of mine did a post and if u want to check it out here it is : https://www.reddit.com/r/leagueoflegends/comments/9zx0yq/toplane_from_a_tank_players_viewpoint/