Success of grouping entirely depends on the technical implementation. And new user experience is something that Fediverse sucks at as a whole. On Lemmy, introducing new users to groups could be as simple as suggesting pre-created groups on identically named communities, they can follow with a single click. Which would cover 95% of people coming from Reddit. And for the rest 5% that want more tailored experience could create custom groups.
If !databreaches became the reference community, then it's subject to all the federation/defederation of lemmy.zip, rules of lemmy.zip and laws of lemmy.zip host server and applying it to the whole Fediverse.