The Overpowered and Unkillable tanks

As a devoted player for a year now (I know i'm still a noob) I have some growing concerns and thought this would be the best way to reach you. Certain champions (Illaoi, Volibear, Tahm Kench, and Dr. Mundo just to name a few) are usually built full tank and are encouraged to do so because they become un-killable. (Tahm has grey health and a shield, Illaoi has built in life steal which becomes insane when ulting, voli has a passive that allows him to regenerate 30% of his health, and Mundo's ult regenrates 60% of his health at rank 3) This issue with these champions is besides being hard to kill, which is not inherently bad, they do more damage than champions that are meant to carry games, thus leaving gamers outraged especially when more than one of them is on a team against you. I strongly advise you look over the damage output on these champions and consider solid nerfs to damage.