As an adult I agree on principle, but how old are your kids? The social pressure to be present in these things must be tough to deal with as a teenager. Can they still access it on a computer?
I was an uncool outcast in school. Now, the "cool kids" from my high school bag my groceries when I go shopping. Social pressure is what got them to where they are. Not succumbing to it is what got me to where I am. I am OK with my kids hating me for now. They'll thank me when they can afford things they want while the former "cool kids" waste their lives bagging cabbage.
I urge you to take your kids' complaints seriously, your comment reads quite dismissive with some strange generalizations of how "cool kids" and "outcasts" will do later in life.
Pressure can turn some people into diamonds (you, apparently), but it can also crush them psychologically.
I struggle to think of time on Instagram being well spent. Perhaps less badly spent?
Also I wonder how they'll do age verification and "parent" verification, might end up being very trivial for most teens to work around the restrictions using secondary accounts. Thinking about it, the policy might be more for show than anything else.
In my opinion the addiction cost likely outweighs the benefit in this particular example, especially since there are so many other less addictive ways to get inspiration for art.
A friend recently mentioned an online jewelry retailer called Frank Darling [1], which sells both natural and lab-grown diamonds.
They have a pretty interesting business model: they're mostly online, but also offer in-person appointments with a designer and offer to 3D print pieces in resin before producing them.