'Wait,' I hear you say, 'Instagram had a standalone direct messaging app?'
It did, kind of. As noted, back in 2017, reports surfaced that Instagram was developing a separate direct messaging app which it was framing as another rival for Snapchat. Instagram had already taken over Stories at that stage, but Snapchat remained sticky with its user base, largely due to the popularity of its messaging functions.
Instagram saw Direct as another opportunity to hit Snap where it hurts - Direct was initially launched Uruguay, Chile, Turkey, Italy, Portugal and Israel, regions where Snapchat had not yet gained a foothold. Using the same strategy as it did with Stories, Instagram sought to offer Snapchat-like messaging tools in markets that Snapchat hadn't yet focused on - which, eventually, would help them negate any future efforts by Snap in those regions, because users would already have access to the same tools, with their established social graphs, within Facebook's apps.
Eventually, Direct was rolled out to more regions, but it wasn't heavily promoted, and Instagram maintained that it was only ever a test. According to TechCrunch, the app had seen around 1.35 million installs worldwide, with the largest percentage of those coming from Turkey and Italy.
Those numbers are not enough to sustain the development and maintenance resources required, and with Facebook looking to integrate its messaging tools across its main family of apps, there's no place left for the separate Direct tool. So it's being rolled back.
As noted, given the small number of users, and the general lack of awareness of its existence, the impact will be limited, but if you have used it, your conversations will automatically switch to Instagram.
Farewell Direct - we barely knew thee.