I am a photographer who uses Lightroom collaborative proofing. I want clients to be able to make image selections without having to sign up for their own Adobe ID.
Although it is free most people don't want to have to sign up with another username and password to a website that they feel they are likely to never use.
The workaround that I've been using is supplying my clients with an email and password for an additional 'free' Adobe account that I have setup however this only allows 5 people to use the credentials before it requires 2 factor authentication (making this system unusable).
If proofing selections were able to be made by 'anyone with the link' it would make the system much more usable to so many more people.