Sure, this is a fair use case. But then can't the browser tell the end user that someone wants to read this browser data so the user has a chance to say "no"?
Re:Browser Fingerprinting: A Survey
by dredmorbius on Tuesday May 07, 2019 @07:35AM
(#19848459)
Changing user-agent is virtually always possible, though a vanishingly small fraction of users will do so.
Bundling into adblockers or browsers directly would help.
For instance, several versions of Firefox had a serious bug in shared workers, which appeared intermittently when users opened your site in multiple tabs https://stackoverflow.com/questions/51092596/feature-detecti... - I had to use the user agent to work around this.