Had a feeling that this entire post was just privacy “purists” taking something a bit too far. I’m not confident that knowing the size of your browser window is enough to definitively ruin your life.
This is frequently some of the most identifying bits of information about you. Have you try the eff's panopticlic? It'll tell you how much the combination of things like your resolution, available fonts and available extension can identify you 1 in a few hundred thousand or million of visitors. This is a legitimate concern for a privacy oriented search engine that claims not to track you.
1) Just because it's possible to use this in an aggregate fingerprint doesn't mean the collection of this one datum in isolation is actually for fingerprinting
2) Given the context of the actual API call, this is probably for benign purposes and not for fingerprinting
https://panopticlick.eff.org