no offense, but i don't think copying reddit posts is the best idea to convince more people to join. when people say they want content on a social media platform, they generally mean organic, fresh content as opposed to stale & regurgitated posts. while the idea will probably catch a few temporary eyes, i don't really see many people staying on a platform for what is essentially an archive of years old topics. i mean after all if a lemmy instance is just a snapshot of old reddit posts, then why not just go back to reddit & get that content + the newer content too? even for those that do, if people are anything like me they'll want to actually see the original comments of the thread & not being able to do that will likely just frustrate them.
additionally, archived/mirrored reddit posts are already everywhere. you can likely find the top 100 posts of reddit on a youtube video or some random site already. do we really just want to be another reddit repost mill? you also have to consider the demographic - most people switching to lemmy are long-time/heavy users, because many casual/new users don't care enough about the situation to leave. those long-time users have likely already seen all the top r/bestof & r/all posts on the site, some of them getting popular many times over the years, & probably don't want to see them again.
imo the best thing that lemmy & the fediverse can do is be our own thing & focus on quality > quantity. this is not a for-profit platform, so i don't see the need to try & convince every reddit user to switch.