Riot, doesn't "Balance" mean that everything should be about equal?

If so, then why does a Marksman get to four-shot me when I've built full tank? Let's be real here, Armor feels like it does quite literally nothing past 25 minutes.

If a Marksman gets to penetrate through 30% of my Bonus Armor, why do I not get an item that negates 30% of their Bonus AD? Shouldn't I get some sort of item that allows me to shrug off, let's say, 1 Lethality per level? Shouldn't I get some sort of item that allows me to, I don't know, reduce their Lifesteal ? Can't I have some sort of item that grants me movement speed on being auto attacked, so I can stick to those carries? (Would have to be 100% defensive item, or bruisers would buy it every game)

Tanks feel weak. Every time ADCarries are buffed, they feel weak. Every time any role is buffed, they feel weak. During the "tank rework", all that happened was a straight, across the board nerf to tank items. The Marksman rework only buffed them. The only time I've ever FELT like a tank in the past 3 years, was when I played Poppy with 500 armor against a full AD team.

Can we finally do something about this? I honestly see no point in playing tanks right now, when ADCarries and Assassins rule the map.