If Instagram users could post links willy-nilly, they might even be able to connect directly to their users, getting their email addresses or finding other ways to communicate with them. Links represent a threat to closed systems.
On CodePen, we have a TextExpander snippet we use for every single Instagram post we schedule through Buffer and it expands to this:
Looking for the code? It’s open-source on CodePen, follow the link 🔗 in our profile and find the author’s Pen there.
I can’t quite explain it, but I feel taken in by this sleight of hand. My brain goes, “Oh, they just can’t allow links on Instagram posts because it would just turn into a cesspool of spam and bad behavior.”. But of course, that isn’t the real reason. Instagram is already a mess of spam, and it’s fairly easy to avoid. Links wouldn’t change that. If anything they would be a helpful honeypot for catching bad actors. Links just make it easy to leave.
Minor note about linking out: Business accounts with over 10,000 followers can add a URL as a “swipe up” gesture on Instagram Stories. Whoop-de-doo.