Runes have a gigantic impact in early levels. I may or may not be high elo depending on your definition. I'm currently p2 and was diamond the last two seasons.
The reasons you probably don't see the difference is because of one of two reasons (or a combination of both)
- Low elo players tend not to abuse certain powerspikes/early level advantages because they don't know the matchups well enough. This makes it so nothing happens early game where runes are most potent (because standard runes are often non-scaling runes)
- They don't look at the opponents runes, so they can't abuse a mistake/choice in an opponents runepage.
Here are two examples. The first is only to demonstrate my first point, and the second shows a 1v1 with different runes to showcase the power of runes.
Example 1: Lets assume in botlane there are no supports for the sake of simplicity. The matchup is Lucian vs Caitlyn. Normally, Caitlyn should win this matchup handily and often does assuming both players are of equal skill. However, a skilled Lucian player can take advantage of powerspikes to swing the lane in his favor. Lucian shoves the lane and gets level 2 before Caitlyn does. Immediately, he levels up his dash and goes in on the level 1 Caitlyn. Caitlyn took either Q or W at level 1, and takes a horrible trade. A worse player would've sat back with that level 2 and done nothing. The timing window in this case was 2 seconds before Caitlyn last hit the minion she needed for level 2 as well.
Exmaple 2: Zed vs a Twisted Fate matchup. Zed looks to poke at level 3 with a full combo of W>Q (He hits both his own and the shadows Shuriken), and a E with the shadow.
Assuming TF did not take Armor runes, he takes 25.2/(100+25.2) = 20.13% less damage from the combo from his armor (which in this case is only his base armor)
Assuming TF did take flat armor seals, he takes 34.2/(100+34.2) = 25.48% less damage.
That doesn't seem like a lot, but think about how much damage that saves you from his poke damage over time before you get Zhonyas. At level 3, TF has 643 health. Zed has to do 32.15 extra damage (assuming everything is physical) at level 3 to kill you in an all in. With how often League comes down to small margins, that is incredibly useful. How many times have you lived with under 50 health from Dangerous Game?
Another example that might be easier to see the impact is scaling CDR glyphs. You can get 10% CDR from glyphs at level 18. That often is 3-4 seconds off your rotation. Think how useful it could be to get another rotation off in teamfights if you just had a couple more seconds.
