Instagram today is a bloated, algorithmic mess that doesn’t know what it wants to be

It knows what it wants to be. It just doesn't care what you want it to be. Its' main goal at this point is to exploit the massive userbase to push more and new shit. Trying to start a new platform for it would undoubtedly be unsuccessful. Just look at Threads. Frankly I'm shocked they didn't just shove microblogs into IG as well. You see the same thing with every successful platform with sufficient userbase, they just abandon their identity in favor of shoving new and more shit down your throat until it becomes said bloated mess and the experience in general is awful, but they know you won't leave because there's no viable alternative that isn't also doing the same thing.