I typically see software from the perspective of software freedom. When a user downloads a web page from my server, I can temporarily record that an anonymous

I typically see software from the perspective of software freedom. When a user downloads a web page from my server, I can temporarily record that an anonymous user made a request because I'm only logging what the software I'm running on my machine is doing. After that, the user should own that downloaded copy of the page and use it freely without surveillance from me or anyone else. The only restrictions in place are those set by the license (hopefully AGPLv3). Beyond those restrictions, the software doesn't belong to me anymore so I don't collect metrics. It's true that I won't be able to get detailed metrics about what the user is doing, but it's also true that user's copy of my software will only be serving the user directly. Web apps aren't different from other software; telemetry and user studies should be opt-in, transparent, and sent back only with informed consent. Only then can I consider running analytics.