@evan i think most mastodon clients don’t want to parse “raw” activitystreams in addition to parsing mastodon api responses. the closest they’ll come to that is requesting the public mastodon api endpoint for the root statuses/:id/context (which is maybe “more complete” but not guaranteed to be “fully complete” either — if some downstream replies drop the root server, then they wont be included) (also the mastodon api limits context to 4096 total entries and gets inefficient long before then)
@evan i think anyone who wants a “complete” view ought to stop expecting that for replies (short of recursively crawling the whole web) and instead work toward a distribution model where conversations exist in some context and are managed by the server responsible for that context. (see fep-7888 for a description of how context could work normatively, but tldr: send your Create to the context.attributedTo and they’ll distribute an Add which you can forward to your followers)