CHOSEN FOR ACCESS AND CONVENIENCE
12 point sockets were traditionally used to allow drive tools to be positioned more conveniently in days when ratchets were coarse toothed and so weak breakers were neccessities.
When a ratchet could not be used, it was faster to remove or install hardware with a 12 point since we could turn further before we needed to remove the breaker and reposition it.
Box wrenches have 12 point profiles for the same reason.
Typical mechanics' tool kits, just 20 years ago, had 6 and 12point sockets in every drive and depth.
ROUNDING BOLT HEADS
Snap On's Flank Drive socket geometry was designed for 12pt initially, not 6pt, to reduce the common occurrence of bolt head rounding caused by the plastic yielding of hex head fasteners' corners. Corrosion was also more common just 20 years ago, before Cad plating, zinc plating etc became so ubiquitous and contributed to the frequency with which we encountered the problem of rounded hardware.
Technically, flank drive 12 pts and 6 pt hit the bolt head in the exact same place and with the exact same sized contact patch, all other things being equal. Either a 12pt or a 6pt will do an equal job at removing hardware. The difference comes in when the head is damaged, or we damage it, or its corroded, in which case the contact patch on the socket moves closer to the corner such that a 12 pt can skip or slip and a 6 pt won't. For this reason, many mechanics prefer 6pts. But they aren't always helpful which is why some people don't encounter any problem using 12 pt sockets.
DO WE NEED 12PT SOCKETS?
With the advent of super strong, fine toothed ratchets, we no longer need breakers or the 12pt sockets we used with them for their original purpose.
For modern automotive work, almost regardless of vehicle origin, 12pt sockets are still needed for the 12pt fasteners found in engine bays, brakes, and suspensions. But I find I need them only in the larger metric size so my only metric 12pts (besides my wrenches) are 1/2" drive. You could treat these as specialty fasteners and buy individual sockets as you encounter need for them.
But I hasten to add the only disadvantage to using 12pts is removing compromised hardware. If you don't regularly encounter old, corroded, or stuck hardware, 12 pt sockets can be easier and quicker to install.