North is a weak player, East and South very good and West fairly good
Over the double of 3♣ North was afraid to introduce ♥'s knowing that was one of East's suits and gambled on rebidding his ♠'s
South bid 3♣ to show North where his strength was so they could make and intelligent decision if E/W bid over South's eventual 4♠ bid
Benefits include:
Plus... it's free!