Complex sentence: This move by MSN and Multiply succeeded in killing off a large number of MSN Groups communities, because the migration process was rather complex, essentially creating a new group, importing content from the old one.
Split into simpler sentences: This move by MSN and Multiply succeeded in killing off a large number of MSN Groups communities. This was due to the fact that the migration process was rather complex, essentially creating a new group, importing content from the old one.