I would say reddit’s golden years were around 2012. Since it started around 2005 that gave it 7 years to get as good as it was in 2012. If Lemmy follows the same formula, it may take about the same amount of time, but reddit saw exponential growth when Dig shot itself in the foot, much like reddit is currently doing, so it’s possible we may get a jump start. Who’s to say really?
I would think longer than Reddit as you have to be a certain level of tech savvy to wrap your head around the overall concept of the Fediverse (especially if all you’ve ever known was traditional social media).
Probably 2 to 5 years. Lemmy kinda just works and is usable right now. To become better than Reddit the experience needs to be seamless.
The content already is better!
Depends where you go. For instance, the discussions in AskLemmy seem better than the discussions in AskReddit right now, but lots of communities are basically empty still. The main baseball community on Lemmy.ml only has a few highlight videos posted, pretty much all from the same user. The corresponding Reddit feed would be much more active with both posts and highlights. It’ll take a bit of time before enough people migrate over to start posting content again.
