Frequently people asking CSS questions in DA, Why can't we have the option to migrate to stack overflow which is on-topic there? Currently it have option to migrate only to MDA. On the other side it really save the time for OP.
There isn't a migration path to other sites because we don't have much questions that need to be migrated to other sites. Considering the rejected migrations (migrated questions that are then closed in the receiving site), those numbers are even lower.
For the past 90 days, the numbers are the following.
- Stack Overflow: 15 (1 rejected)
- Server Fault: 2 (2 rejected)
- Web Apps: 1 (2 rejected)
I once asked to add Stack Overflow as migration path, but Jeff Atwood said "It'd be very easy for such questions to get lost in the flood at Stack Overflow." Then, he added "I am disinclined to send these question to SO, unless they are awesome and are not getting any answers at all here."
Keep in mind the first rule of migrating: Don't migrate crap.
Migration is probably reserved for those questions that got very good answers, and for which would be a shame to lose the precious work done from the users who answered. IMO, migration is never done to avoid the OP has to rewrite the question again; that is the less to get worried about.