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Google could kill YouTube Vanced for good
(www.androidpolice.com)
This is a most excellent place for technology news and articles.
If you give thumbs ups and add comments, you're still providing user generated content that increases the value of the content you watched, so they're still getting something out of it. Your contributions could go on to drive someone else to watch the video which could end up seeing the ad you blocked.
It's a question of what that value is that you've provided to the service. It's the same question Reddit will be finding out the answers to over the next couple months.
You can try to look it up if you want, but I'd suspect those sort of interactions are fractions of a penny on the dollar compared to revenue from Premium or Ads.