Migration has a high bar to clear:
- The question to be migrated has to be off-topic for this site.
- The question to be migrated has to be on-topic on the target site.
- The question to be migrated should be of high quality and ready to be migrated to the target site. Bad question should not be migrated. We do not want to just shuffle them to be somebody else's problem.
This criteria thus requires familiarity with the target site to be able to make an informed decision.
This is a lot to ask from five different users. They should all individually be familiar with the target site's rules and policies.
I often see people recommending a different site without actually knowing enough about it. I think having a special migration path should not be given to regular users. With the exception of migration to the per-site Meta. Migrations should be an exception and as such I concur with L.Dutch that it should be left to moderators. They are the exception handlers around here anyway.
To clarify: I do agree that some migrations can successfully be handled by the community. However, I feat that they would not be the majority of migrations. Migrations in general are quite rare, good migrations rarer than that. Having them as an exceptional case seems the most prudent choice to me.