Honestly I don't know why there is so much drama in the sugar glider community. I try to stay away from most of it because I've seen it get pretty vicious. It's just part of the community, unfortunately.
Lineage is another hot-button issue, since there are so many lineaged gliders available out there, breeding unlineaged gliders is unnecessarily dangerous. The risks of unlineaged gliders (and possibly breeding close relatives without knowing) does a lot of damage to the lines, especially for breeders that work hard to keep clean lines. A breeder purposely breeding unlineaged gliders spits in the face of that and implies the breeder had their pocketbook in mind over the gliders well being. Perhaps the new breeder you spoke to was just over-stressing their concern over the breeding of unlineaged gliders? I know I personally would NEVER feel comfortable recommending someone buy gliders from a breeder who breeds pet store gliders/rescues/unlineaged, regardless of how they care for their gliders otherwise. It's just irresponsible breeding.
Also in my experience, if a breeder is cutting corners breeding gliders without lineage, it's more likely they're cutting corners in other places, too. (Vet/diet/safe wheels, etc).
I don't know the breeders you're talking about, but just some thoughts.