The vast majority of French shotgun hunting was (is) done with one or a few people working fields and hedges with dogs ("A la billebaude" in Burgundy). There is a lot of walking to do, and a sling is appreciated.
English style driven game shooting is very much an upper crust exception. Those guns don't have slings. On the same note, pairs are a million to one abnormality.
I guess one does not need a hand guard for walk up hunting.
Best regards,
WC-