Of course it hurts CellNuvo. CN gets paid from the ad supplier, and passes along a percentage of that to us, keeping the rest as profit.
There is absolutely no reason for CellNuvo to do anything to intentionally block higher yielding ads, since they would get significantly less income by doing so. Ergo, CN does not block 15 silver ads-- they're not available to CN.
(Note that CN sets the percentage that we receive as silver, so a particular ad could yield 15 silver, or 30 silver, at CN's discretion.)
Some may gripe about low value ads, but they continue swiping. I don't think the lack of 15-30 silver ads harms CN or swipers. When the dry spells (0&1 silver ads) occur and then CN starts 5 silver ads, there's happiness. It's all relative.
I think last time 30 silver ads were in February or March, before CN introduced Amazon GC program.
When Amazon program started, everything changed, 30 points ads were reduced to 15 points ads.