There are seem to be more young Youtuber or TikTok/Instagram celebrities. I am a little surprised to see that those activities can be considered “EC”.
I see more and more high school seniors building Linkedin but Youtube and TikTok? 
Thought it is better to limit social media access for young children, but that mentality seems to be outdated?
I think it’s legitimate as an EC if the student can show some level of success at it, not that they just spend a lot of time on it. By success I mean number of followers, have they monetized it, created content, etc. I know a kid who has made videos for musical artists and makes money and can point to number of views of his work. Wants to major in video graphic design so dovetails nicely.
I think social media could be a good EC depending on how it’s used. Is the content produced noteworthy in “good” ways? Is it creative, informative, funny, helpful? Does it require special talents to produce? Or is the content just self indulgent?
My son moderates a large discord channel (and I’m not really sure what that even means) but he wrote his essay about it - all the hours spent dealing with online drama, upset kids…it takes a lot of his free time so I think that is a reasonable EC.
Just today my middle school kid told me couple things related to social media. Amazing those stuffs have successfully occupied young minds ^o^
My kid talked about managing Discord as well, even Minecraft teams. These little guys sound so serious. Is that why it’s called “e-sports” . According to my 6th grader, a lot of kids spending time on games or managing their Youtube content, or comparing their “likes” haha. They are proud of this.
I think so, I listed that I was an influencer and received commission on my common app
Long before YouTube was a big deal, one of my kids had a “channel” where she uploaded short films she filmed with her digital camera and edited using movie editing software. YouTube per se was not an EC, but her movie making definitely was.
Technically, it’s “extra-curricular”, assuming it’s not being done as part of a class for school.
Whether it’s a meaningful/good one to list on a college application depends on what it is.
Spending hours scrolling sites is probably not a solid activity. Building a meaningful audience, on a meaningful topic, turning it into a business, having a societal impact, etc., certainly could be. I’d say the bar is relatively high though, as the cost of entry is low. A generic “Created a channel on X and accumulated Y followers” probably isn’t a meaningful differentiator.
I know quite a few young adults who are influencers. They make very good living out of it, in the six figures. It’s a full time job for them. I don’t see why it can’t an EC for a high schooler. They are just new medias now.
If you are a kid, and you have social media skills, have design skills, have built a significant audience, are considered an influencer, are working with paid promotions - that’s all really valid stuff if you are applying for a business or marketing degree. My babysitter started a non-profit and her social media reach for that organization is BIG and really impressive. (She’s an impressive young woman…) I think it’s just as valid as an EC as anything else. Maybe more valid than a Quidditch league…but again, that depends on where you are applying.