In my opinion we're already more or less at the "functional" stage. I can browse the place and shitpost and stay entertained for quite a while, with new content coming in while I do it, so that if I'm so inclined I can spend a full day pissing away my time on lemmy. It's nowhere near Reddit yet, where I could pick any given topic and read almost infinitely on it, but that's a function both of time and size, and not a reasonable expectation for a brand new platform. As long as the numbers we have now are sustainable they'll become self-improving in that direction.