My Weim has hers still although she is docked and I've seen her use them to grip when she's cornering or changing direction (and when she tries to climb trees after squirrels

). They've never caused her any problems but her's do 'splay' a bit which concerns my vet but having seen her in action, I don't think it's a reason to remove them.
My show cocker doesn't have them - he will be 3 yrs at the end of May.
Some dogs have them - some don't - it's a prehistoric throwback to when the prey had to be "held" for the kill. They are cartilage ie not bone in very young puppies ie 3/4 days old, therefore were often removed when pups are tiny, rather than wait for severely damaged dew claws having to be amputated in adult dogs when the cartilage had changed to bone.
There can be some really nasty dew claw injuries which is why many vets in the past opted to remove them at 3 days old.
Dave's were removed when he was a few days old, I know that, but not sure who or how!