I wouldn't put the decentralization aspect of Lemmy in the spotlight as its implementation has signifficant flaws. Lemmy hides posts and comments from users in defederated instances even if they're posted on communities that would be otherwise visible, and this makes the optimal behavior for visibility be that of creating accounts in every instance you're posting to.
The previous accounts i've used on this instance, [email protected] and [email protected], had far less activity on posts/comments compared to posts/comments made by others at similar times, because the instances they were from were defederated by nearly all lemmy instances over accepting lolicon. This issue was bad enough to be one of the reasons that made them leave Lemmy entirely.
I think most users leaving reddit over current grievances have already done so, just not necessarily on this instance.
IMO the best idea would be waiting until reddit does their next majorly unwelcome change and only try to move users from it at that moment. Creating a new account on a different website has its friction, and i don't think any amount of pushing within /r/futurology's own capabilities can overcome that on its own.