Is tankiness toxic?

I should start by defining some terms.

By tanks I mean the traditional tank, a character who's job is to wade through damage by nature of their tankiness.

By toxic, I mean something which lacks most (or all) forms of counterplay. This does not necessarily mean they are overpowered.

By counterplay, I mean an action by a player to avoid or reduce the effects of an action taken by their opponent, usually by outsmarting them.

By counterbuying, I mean buying items which will help you against a particular enemy. This can be considered a from of outplay, but will not be considered so for the purposes of this discussion.

We talk a lot about how certain champions lack counterplay. Trist was changed to help with this and Zilean is in the woks with similar changes. Characters like those, when strong, were oppressive, mostly due to the lack of counterplay involved within their main poke abilities being targeted. The only real counterplay opportunity was the time these abilities took to activate, with trist's e having travel time and Zilean's bombs having a set time before going off. This gave opportunities for allies to assist you with a shield or heal, but not much else. You could try to stay out of range of these abilities, but most champion are unable to do so realistically.

In order for something to not be toxic, it requires the player to be able to make reasonable decisions to avoid what their opponent is trying to do.

Now, what counterplay is there to a fed tank? you cannot outplay their health. Take a tank with no mana and no summoners. there is nothing a skilled player can do to kill the tank faster than a completely new player. You simply must whittle away at them. While this is true for any champion, tank or no, it is far more obvious with tanks. Health is a buffer, which allows a player to make mistakes up until a point at which they die. The more health you have, presumably the more mistakes of equal severity you can make.

Because of this, tanks themselves aren't the problem. Tankiness as a concept is.

All other roles have some form of counterplay most of the time. Many mages have skill-shots o AOE abilities, which can be dodged, while assassins are extremely vulnerable to cc and must be close to an opponent to deal damage. ADCs are generally immoble and either have dps or burst with a smaller amount of dps, which can be played around. Etc. Etc. However, there is no skill involved in building tanky. It is possibly the only role which only requires counterbuying rather than counterplay.

How would you fix this? I personally believe that making tankiness reliant on active abilities would fix a majority of the problems. Something like Vi's innate or Kassadin's q, but to a greater degree. Make tanking an enemy require you to outplay them. Make tanks just as squishy as the rest of the champions, but have certain abilities give them short periods of extreme tankiness which can be played around.

What do ya'll think?