Like any other patch, we use the champion balance framework to determine which champs to buff and nerf for Worlds, but the types of changes we make are likely to be more focused on pro play. For example, if we have high confidence that certain champions will have a 100% presence at Worlds, we are likely to try to address this via direct nerfs or by buffing counters. Akali and Aatrox have both seen recent nerfs on account of this expectation. Another thing we generally try to avoid are extremely low-lethality metas for Worlds. A recent example of this is Tahm Kench—we expected him to have a very high pick rate and somewhat low ban rate. We think that at such a high presence, he degrades the quality of the play and viewer experience. As such, we reduced his early safety in patch 9.19.
Assuming this is what you're going off of, you're completely misinterpreting the context of it. When they say low-lethality, they don't mean "people who have low kill potential", because their example is Tahm Kench, a tank whose had no issue killing folk these last few patches. They're talking about Low lethality in terms of "They actively stop plays too easily", leading to points where mistakes can't be punished. Once again, Tahm Kench is the example here, a champion whose been an issue in the past due to too easily negating plays and picks with his Devour.
Worlds is a spectacle event, no one wants to spend hours watching nothing happen, and then one fight decides the game. Riot's quote isn't even saying "Low Lethality champions", it specifically says "Low Lethality Metas", meaning, games where nothing happens. Tanks are anything but low lethality, because they are active play makers, making picks and engaging fights. They are everything that Riot wants with worlds, people actively picking fights.
What Riot doesn't want, are games where nothing happens, because no ones mistakes can be punished.