I don’t know that it is meant to be a drop-in reddit replacement. That’s an assumption that goes too far IMO. I think it’s certainly intended to have a lot of similar functionality as reddit, but the nature of it being decentralized tells me right off the bat that it’s not a drop-in reddit replacement. That being said I do think there is a balance in striving to make it easy for people to onboard, especially reddit users looking for something else, but I also understand that keeping out bots and spam is critical.
It’s easy to say it should be changed because we don’t know what would happen if they changed it, but if the site did become overloaded in spam, that would be even more of a detriment than slowing the growth because people have to wait for approval. At least while others are waiting for approval, the people already here can use and enjoy the platform. If you get rid of that and it becomes loaded with spam, then no one gets to enjoy the platform.
I think the difficulty with a place that has such a low userbase that then grows rapidly is not having a lot of established active moderators. There’s a lag time to some extent to getting active and responsible moderators. Plus not being a moderator nor an admin on Lemmy, I don’t know the capabilities they have at hand, but I know with reddit the moderator tools were built up over time. All of the automodding capabilities they have now didn’t exist at the beginning, and the automod tools are what allow them to handle such high numbers of users. I suspect Lemmy probably doesn’t have extensive automated moderating tools at their disposal at the moment if I consider other deficits that Lemmy has at the moment.