silverpill on Nostr: The content attribute is to contain the WebFinger handle of the author's fediverse ...

The content attribute is to contain the WebFinger handle of the author's fediverse profile, i.e. username and domain separated by an @-symbol. A leading @ can be included and ignored when processing. This format was chosen for its user-friendliness, as this style of handle is what users would be used to seeing and typing when using most fediverse software.

This choice was criticized a lot when the feature was introduced. Meta tags are primarily read by machines, not humans, so user-friendliness shouldn't be a concern. Reliability, on the other hand, is worth taking into consideration. preferredUsername and the user part of a handle can be changed at any time. Actor ID is a more stable identifier and in my opinion is a better match for the fediverse:creator tag.