Let's be honest now, tanks are just bad design.
They enforce a type of gameplay where it is literally beneficial not to interact with them. The the items that tanks purchase, like thornmail, sunfire cape, frozen gauntlet, and the stats they acquire from stacking these types of items, are designed to make attacking or standing near them something that should be consciously avoided. Furthermore, it is strongly advised that you don't waste your time ganking tanks because shutting them down is pointless and a wasted effort in the long run.
In almost all situations, it is in the best interest of you and your team to just...ignore them, as best you can.
Something needs to be addressed.