Reddit was and is impossibly easy to use. You visit the site and start scrolling. If and when you decide you want to participate you create and account and start doing so.
The barrier to entry on Lemmy is much higher. This will keep out many of the types of low effort users that would eventually turn this into reddit.
Maybe someday the fediverse will be as obvious to everyone as any other part of the internet but it’s definitely not right now and it will be awhile before it is.