It's much more than that. :) If you have a large collection of photos uploaded to google, you can make some pretty insidious searches that will return extremely accurate results.

Try searching "bikini" if you have any snapshots from your beach vacation uploaded. Even with all location metadata/camera information stripped from the images, Google was able to find 99% of them using keyword searches like that. You can go further and search specific body parts, too. I think that's pretty creepy as well.

The typical HN response is to dismiss arguments like this with, "Well, don't be so careless to upload photos in the first place!" but what happens when laypeople use Google Photos as marketed and as a backup service for their entire lives? I don't think those people would be comfortable knowing that Google can not only accurately identify 1) people and their friends implicitly and 2) identify when those people are scantily clad or nude.

Just imagine a bad actor getting access to your photos via Google and being able to instantly pull up any compromising or sensitive information you may have forgotten about with a simple keyword search because that's something they, for some reason, index.