I do a lot of magic on my personal Instagram. It's not for exposure or branding (the account was private until recently), but just because my friends say they enjoy it. I do a video every Monday. Because it's just for fun, I can be as creative as I want with the method or presentation, without a lot of pressure to appear very professional. Not only does making these videos allow me to flex my creative muscles, but I'm able to get really good feedback about what I perform, which is pretty valuable to me. If I ever want to use the tricks in the videos at a gig or in a professional show reel, I'll know which ones fool people and which ones don't.
As for a lot of magicians performing the same tricks on social media, I don't see that as a problem. As a magician, I follow a lot of other magicians, so I'm bound to see the same trick a couple of times. Laymen, however, probably only follow one, maybe two magicians on social media, so I doubt they would see the same trick twice. Also, laymen would probably not even remember if they saw the same trick, because they wouldn't recognize the trick by name from seeing it on magic websites.
Finally, I'd say that a lot of magicians think it is easier to become well-known on social media than it actually is, and that, I think, is due to the availability heuristic. Rodney, a magician himself, might be able to think of quite a few magicians with big followings on Instagram or Youtube, so he believes that it's easy to become popular on social media. Rodney isn't basing that belief on a true representation of magicians on social media, however, because for every magician with a lot of followers that he sees, there are hundreds, if not thousands, of magicians with very few followers that he doesn't see. Rodney simply doesn't see these magicians without a lot of followers because, well, they don't have a lot of followers, and so they have no exposure. The big magicians on social media, however, are very easy to see because of their large follower base. This means that Rodney sees lots of "successes" that have made it big on social media, but doesn't see any of the "failures." I think a lot of young magicians are like, so they are a little too optimistic that they can easily make it big on social media, and don't realize all the hard work, and luck, that it takes.