Regramming is something that many people do on Instagram, which is basically taking someone else’s post on posting it on your profile as a way of sharing. However this is done through the use of third-party apps as it has yet to become an official feature, although last year it appeared that Instagram was testing out an official method.
That feature has yet to go live, but now in a report from TechCrunch, we could be getting some kind of variant of it. However instead of the post being shared to you Instagram profile, it will instead be shared in your Instagram Story. Instagram has confirmed that they are testing the feature with a boilerplate statement that reads, “We’re always testing ways to make it easier to share any moment with friends on Instagram.”
As to why Stories instead of your profile, that we can only speculate. Given that Instagram is sometimes used as a portfolio of sorts for some users, perhaps Instagram wants to keep the profiles of its users free of shared posts and contain only posts of their own. By sharing it to Stories, it can provide the same reach except that it will expire after 24 hours, plus there might be some users who don’t want to have their posts regrammed.