Damage creep is real

No, you have a very rigid, far to narrow connotation of a term which can be applied in macro and micro scales and to various different attributes within a game, or to the game itself, and are then substituting this reductive connotation for the denotation of the phrase, then are calling others out for using a more expanded use of the term.

The meta of season 7 involves supports with much higher damage capabilities than the meta for season 5. Whether or not the damage of those champions in their kit alone have been damage creeped, or not doesn't actually have any barring on that fact as we are not looking at those champions individually in a vacuum from from all other constraints and lurking variables.

That depends, honestly. If your 4 ADs have no CC, you're better off bringing a lock-down tank. or maybe even (who is somewhere between a tank and utility support).

No, they need MF support and then wonder why they can't kill the Nautilus

Lethality has a ratio that scales, true, but you can get a lot more than you could before. It used to be that you could get ~60 or so (full built) and total glass cannon. With Lethality, you get 60% of your Lethality as actual armor pen if your target is level 1, but at 18 (so we can compare full builds) you can have 85, but that's with an extra Serrated Dirk, so realistically 75, and this isn't counting Last Whisper or Black Cleaver. Then you have the extra damage from Duskblade that scales with Lethality for another 75 + 2*Lethality -> 225 true damage.

Not only is the pen much more available now, and in great quantities, but the items it comes on are better. This is especially bad when you consider the order that armor pen works:

1. Flat Armor Reduction (Nasus' E)
2. %Reduction (Black Cleaver)
3. %Penetration (Last Whisper vs Bonus Armor)
4. Flat Penetration (Lethality)

Suppose Sion build Ninja Tabi and Dead Man's Plate and was level 18 with no runes/masteries to add armor. He would have 154 total armor: 74 base + 80.

An enemy with full Lethality + Last Whisper (like a Varus using his Q) reduces it like this.

80 (bonus armor) * (1-.45) = 44 74 + 44 = 118 118 - 75 = 43

Damage reduction is 44/(44+100) = 30.5% Without the armor pen it would be 60.6% Against a 300 AD attack (ignoring Tabi's passive for the moment), this is 209 damage rather than 118. He takes 77% more damage.

Ashe has 79 armor at 18 with no defensive items, runes, or masteries granting armor. 79-75 = 4 armor -> 3.8% damage reduction as opposed to 44.1%. Against a 300 AD attack, she takes 289 damage as opposed to 168. She takes 72% more damage.

That damage multiplier looks awfully close to the amount of Lethality we have, doesn't it? That's not a coincidence. The armor formula is DR = A / (A+100), which means you gain 1% ehp for each point of armor you have. Inversely, Lethality reduces your ehp by 1% for each point they have. It is a damage multiplier, and we now have access to a lot more than we did before--even after the LW change--especially since LW is only really good against tanks now, so assassins can usually skip it if they are only concerned with sniping carries. Instead, they can do something more like:

(whichever upgrade they feel is best for that match, likely Tabi) Two of: Or LW if they really feel like it and the enemies are pretty tanky.

With just the Lethality items, they also gain 180 AD, and will probably build another 120-160 or so with their last 2 if they don't absolutely need purely defensive options. This just reinforces the point I made earlier, which is worth mentioning again:

Not only is the pen much more available now... but the items it comes on are better.

The only way that Lethality is worse than old armor pen is that it has slightly less raw value at lower levels, but this mostly goes away after you have finished your first Lethality item and most players are level 9+ (since old armor pen was about 80% of what is available now, and level 9 is when players receive 80% value from Lethality--break even point).

Type in "S7 Full Lethality" in Youtube and tell me what you see. Sure, some of those may be troll picks, but honestly it just points to the problem when you even see Soraka players doing it and getting away with it (even if that is far outside the norm).

inb4 "lowelolol"