@darius most social media sites have places on profiles where you can put links that no one else can touch, and that's something that can be scraped. no one else can edit my twitter bio or profile website link on my other socials. if your main internet presence is on instagram and you're joining mastodon, the HTML that displays your public profile data is the most appropriate place to be looking for a link to your mastodon account. you don't need the HTML rel link at that point.