You've been playing since Season 4, not season 2...
You're just like most people who come on the boards complaining about the state of the meta - saying you've been playing for so many years and seeing the game change makes you sad.
The game has been in much worse states than this, this isn't even the peak of tank meta - remember late Season 5? Everyone was tank. Even playing adc tank was viable (Morde), because everyone did damage and items favoured tanks.
I see you main adc/mid, but you don't adjust your build at all. Always the same.
Try getting tank-killing items like Lord Dominik's rather than assassin-based items like Duskblade.
+1.5% damage per 50 HP difference, capped at 500 HP difference, plus the 45% bonus armour pen.
Tanks these days almost always get Iceborn + Sunfire, giving them 95 Armour. You penetrate most of it.
You say they have 5k HP, well that's not quite accurate - maybe 4k at most.
As an adc/mid you should have around 2000 base HP, meaning there's 2000 HP difference.
This means Lord Dominik's will almost always give max. damage bonus, so killing tanks should be fine if you know how to kite properly.
Whilst turret diving is easy these days, it is avoidable - simply by walking away if you know it's going to end up with you dying.
Outer turrets are fine to lose, you should be able to trade one for one - if 4 members come bot side to turret dive you, your top lane should either be looking to tp to counter-engage, or pushing in top to get the turret.
If you're getting dove under Inner Turrets, call your team. The enemy have no turret for a long way, so have to risk fighting. Usually siege's start with 2 or 3 pushing in the minion wave just before reaching your Inner, giving your team enough time to get down to your lane to help you.
Mid lane siege's on the Inner Turret aren't as easily countered, because the enemy have a lot more escape routes. Focus the minions, if your team comp has no wave clear then you've done something wrong in the draft.
You really shouldn't be dived under Inhib/Nexus turrets unless you're on your own. This rarely happens, maybe if the enemy have set up a good split push. Try to get your team balanced out on each Inhib, so you lower the chance of being dove. The enemy should focus the tower and not you, so focus the minions and they can't get the turret. Or, if you have enough burst, you can force them off the turret by putting them on low HP.
and 
or champions that are pretty much giant walls with little to no CC, then please stop calling them tanks.
