Permalink button from a filter is not a permalink to the filter, it's a permalink to the query which is completely different. The filter may change over time as the author of the filter modifies it, this makes it much more useful than a query link since the query link.

From this page I had a hard time figuring out that I could send around the link the fact that the URL parameter was requestId made me think that the location was specific to me. (assumed the request id was somehow tied to a session or something). In any case I looked for a permalink button, found it, and later realized that I'd link people too a query instead of a filter that I could change.