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Oil designers understand that it is not possible nor is it necessary to produce an oil that is both super light and has a low Noack. The lightest 0W20 oils run very clean and have Noacks around 12%. Noack is not meaningless. It is simply not as important as other factors. The threshold remains 15%, while oils are now required to be easier on emission systems, produce less sludge, and maintain cleaner pistons, amongst other things.
When Noack gets to 15% or above, the chemistry of the oil starts to change to the point that it becomes a concern. Below that level, it's not so much of a concern. Thinner motor oils are getting so good, that even the "thick oil people" on Bitog have had to adjust their thinking.
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