Can I contribute? I'm on MN for GC reasons but I'm actually a member of the generation allowed to grow up with social media (now young adult, early 20s). Was very unrestricted (clueless parents) and had some sites as young as 11 as I argued my case using other children in school etc.
I can unequivocally say that social media made me an unhappy teenager - the groundwork was already there of course (bullied/isolated in school) but it led me to be even more isolated from my peer group than before and gave me major self-esteem issues.
I was actually more successful talking over Snapchat with people at school than I was in real life, but that brings into question why they didn't just talk to me day-to-day! I don't have happy memories etc. of time spent messaging, it is low-quality time which will fade away
Most social media sites are configured to be addictive, someone with access will always choose them over a less appealing diversion which might be nicer in the long run (books, going outside). A child definitely does not have the faculties to deal with this so it's unfair to impose this on them - you wouldn't let your underage offspring start betting in casinos - it's the same mechanism
Every single social media site contains extreme pornographic or sexualised content to some degree and a curious child will always be able to find it. Eg. Tumblr is 13-plus and until 2018 it was full of hardcore pornography which was easy to find and explicitly allowed under T&Cs (there's still porn now, it's just underground). Similar situation with Twitter and even Pinterest I think
Out of my friend groups I can always tell who has spent the most time online based on how they speak, socialise, conduct themselves. Teens on Tumblr and Instagram are often lauded for being really politically conscious but this is just code for 'can repeat a slogan'... there is rarely any context or actual education going on. Same on YouTube, it's mainly 'infotainment' set up to make money from ads, buy them a book instead
A well-researched book is better than any Google search and I have extreme reservations about schools becoming so dependent on online learning. Looks like we will probably never escape the internet in school, work, etc. so a good idea might be teaching children to use the web intentionally and not aimlessly. Eg. have a task in your mind, do the task, then log off and do something different
I wouldn't mind letting 11-year-olds on Whatsapp if a parent regularly checks their activity and if they also regularly socialise outside of school - it's not a substitute for a social life. If there is certain language on Whatsapp it is probably being heard within school too. You are not invading a child's privacy by doing safeguarding checks although it will definitely feel that way to the child. Tell your child that if they have something private and important to say then the conversation should be in real life, basic adult etiquette. Avoid Snapchat because it regularly recommends obscene sexual news stories designed to shock young viewers, BDSM plastic surgery etc.
TikTok is designed to shorten attention spans, is mind-numbing, has an algorithm pushing attractive girls so viewers end up insecure, is full of sexualised content which goes under the radar, and romanticises mental illness as a modus operandi (similar to Tumblr in the early 2010s, many girls self-harming as a result). I would be anxious about even older teenagers using it.
During A Levels I had a chat with my close friend about this who seemed far happier and better-adjusted than me, very active outside of school and a great student, she had the same opinion/experience exactly and said she would also ban future offspring from social media. This is a common opinion in my generation which I think really says something
I wish my parents had just confiscated my phone all day weekends and after school... the only things that came of internet use are that I'm now very knowledgeable about old films (directors, actors - but could have learnt that from a book in greater depth!) and art (same). I taught myself a language over the internet when I was 16/17 but that required an insane amount of discipline which not even I had at the time and which a younger teenager definitely would not have. Most of the supposed benefits of youth internet use could be attained with a library card, while avoiding the cost to personal development and mental health
I'm happy to answer questions if you want to know what it was like to grow up with unrestricted access to these sites