How else could this be accomplished, especially when we are talking about URL structures that need to be somewhat short in length?
I tend to like the approach Valve takes with Steam, which is to completely separate the "account name" (unique, unchangeable) from the "display name" (non-unique, change more or less as often as you want).
I have uh personal reasons for having done this and I know of others who have as well.
I’m not sure why they don’t roll it out more wisely - though I can say it did cause a couple of bugs until I signed out and back in on every steam device.
Each steam account does have atleast 3 internal unchangable account numbers that are exposed through APIs for developers to integrate with and use for things such as enforcing bans etc.
There is no need to have the public-facing identifier be the unique identifier, nor is there a good reason to do it. ICQ got this right, way back at the beginning. But somehow everyone forgot.
Needless to say, the most prominent and memorable identifier being non-unique has all sorts of uses for trolls and spambots too.
Sure, but it has more uses for people who would like to have a reasonable name. This is just the "knives can be used to kill people" argument.
Of course with unique identifiers you probably don't get to call yourself elonmusk, POTUS or amazon
Since there are a limited number of memorable names available, anyone late to the party gets stuck with non-memorable names. Why not even the playing field?
As another person said further down, it's why we have domain names rather than IP addresses. Sure, the way in which they're distributed might be suboptimal, but not nearly as suboptimal as making everyone have to remember the IP address or rely entirely upon a search function that returns ever-changing results.
But in this particular case, they weren't the early adopters...
The real "early adopter" was robbed of his name, for a (imho) is a lame excuse.
Yeah, there is: it's a major UX improvement, because the URLs at issue are entry-point URLs, which need friendly names for the same reason domains for public-facing services (which are key components of entry-point URLs) do.
It's true that in the general case objects don't necessarily need a URL component that matches their friendly name, but this is not the general case.
I know I personally very rarely type a direct URL. Either it's already bookmarked, or I google it.
Instagram accounts (and similar social media IDs) are often communicated in print, and parsing and accurately transcribing things that work like natural language is a lot easier than something like an arbitrary base36-encoded identifier.
They are also sometimes communicated via orally or via radio, where being able to hear and remember is even more affected by the using natural language.
It's opted in to the problem by deciding that display names need to be unique. It's not right or wrong, it's apparently just been decided that that's desirable for the product.