It's a different type of sync than that. Syncing multicameras would ensure the scanning of each camera is aligned so that the start of a frame is at the same time on each camera. Traditionally, you needed cameras that had the ability to accept a sync reference signal provided from a sync generator by running a dedicated cable to each camera as well as all of the other video equipment like switchers, Chyron, VTRs, etc. In the bad old days, if you tried to switch between two cameras that were not in sync, you'd get a very unclean cut as the H/V sync between sources were not aligned.

Today, switching equipment just "re-stripes" the timing from each input. The need for a house reference is not necessary with modern prosumer gear. For broadcast still supporting interlaced HD, they still run that reference cable.