but what excuse can they give?

It's "the cloud", so it's high tech, advanced, and good for you!

It's sold as convenience same as every other "private data siphoning" and "insert yourself in as an intermediary" make-money-from-adding-no-value scam out there.

This isn't just in Tech: for example banks have been trying for almost 2 decades to insert themselves into the last group of economic transactions out there which weren't going through them - cash transactions - in order to get a cut of it and latelly they finally seem to be winning with touch-to-pay technology that's replacing little cash playments like, say, buy the newspaper.

Consider that there really isn't much more space in consumer society anymore to sell more things unless you trully innovate (proper breaktrough stuff, not the "some thing done for ages but now from a smartphone and over a network" of the last decade) and innovation is risky so well established players aren't going to do it (and even the supposed "innovators" in the Tech Startup world have mostly been copying each other of late and the only trully innovative stuff - last gen AI - isn't actually something that causes more sales), so instead what you have is more monetising of what hasn't been monetised yet (such as private information) and large companies leveraging their dominant position in one area to insert themselves as intermediaries in some other area (the touch to pay example from the banks but also quite possibly the point of Google's DRM-for-the-web).