You shouldn't get damage from building tanky
Out of all the items,
fall into the "make you tanky while providing damage." Out of those items,
and
are tank items, with very few exceptions.
and
are bruiser items, with Black cleaver being the most generalist of the items, given how its passive works.
is also a bruiser item, but more of a niche item for split pushing duelists.
No one usually buys more than 3 of these items in one game. Tanks and bruisers will fill their remaining 3 item slots with 2 defensive items and boots, whereas fighters will probably go 2 AD items and boots. Now I can understand why people don't like defensive scaling attached to skills, such as maximum/bonus health scaling, or resist scaling, but those champs are balanced with that thought in mind.
Yet people get all bent out of shape and say that you should get damage while building tanky. Yet how about not getting tanky while building damage?
all make you tankier while building strictly damage.
all provide lifesteal, allowing you to heal up damage taken in fights, with Death's Dance allowing you to survive from AD threats for longer, BT giving you an overshield, and Mercurials frees you from CC. PD directly reduces damage, and ADs now have GA. Now, you are still not going to see anyone usually build more than three of these in any 1 game, but then that is the same as their tankier counter parts.
An ADC might build
or

if they run lethality,

The point is, nearly all roles have access to both offense and defense by buying items. The reason that most of the time tankier items seem to allow for more damage is that ADCs, assassins and mages do not stack resists, or even buy any for the first 20-30 minutes, allowing base damages and AoE to seem far higher than it is, while the large amount of Armor or MR reduces a carries damage by 50-60% until they purchase their penetration item.