This specific API only works in Google Chrome unfortunately. So we need to stop people from trying in another browser and getting frustrated as to why its not working.
To add to OP's point, this thing in Safari also comes to mind as an example of something that isn't easy to detect and address outside of UA detection: https://github.com/vitr/safari-cookie-in-iframe
Deprecating UA Strings and moving towards UA Client Hints seems like a move in the right direction though.
Assuming these iframes will never work means degrading the experience for all users, when only users on Safari are actually affected. Detecting the UA and branching based on that is a much more pragmatic solution.
- It's not likely to work anytime soon
- "The property doesn't exist or throws an exception or does something else that Chrom{e,ium} doesn't do" provides the necessary fingerprinting
- Adding the feature back later can just be chalked up to "growing pains", it doesn't really set especially unique precedent