If the community as a whole feels that way, then discussion in the subreddit will naturally die off.
So why does it need to be done forcefully with a rule? Why force people to migrate? If Lemmy is so compelling, everyone will naturally switch over and it'll win out.
Lemmy still has the same inherent drawbacks of Reddit, but now the mods have complete power with no admin oversight whatsoever.
The moderators of a community have no right to kill it. If people wish to leave for Lemmy, I welcome it. if the other sub died naturally, I'd migrate over here myself (the same way I migrated to Reddit gradually through dozens of forums dying naturally)
Forcefully trying to kill the sub serves no purpose other than to centralize piracy knowledge, benefit Reddits IPO by getting rid of a hated subreddit, and allow more mod censorship. Also, Lemmy isn't indexed by google, so you're fully reliant on the inbuilt search unlike Reddit. (which makes Lemmy less useful for finding specific content)
Lemmy is still in it's early stages. I'm a part of 1k+ communities on Reddit and fewer than half have a prescence on Lemmy or an equivalent.
Dearth of NSFW content. (I mean really, it's kinda sad. Even twitter has more regularly posted nsfw than Lemmy.)
UI and UX are garbage. I've had more 503s on Lemmy the past week than Reddit the past 8 years. The new reddit app looks & feels better than any available android app for Lemmy. (and honestly on desktop too)
Why 'move' ?
If the mods don't want to moderate the old sub, then pass the torch.
Considering piracy's focus on decentralization, y'all are oddly supportive of centralizing your content on a Lemmy instance hosted by one guy.
Which brings me to:
I'm sure this will get downvoted to hell, but these are a few reasons why the Reddit community shouldn't be killed.
I haven't been able to upvote a post in a few days.
Every one just sits there for 60s then: