I am certainly not a precious lawn owner. That comment in itself is rude.
These are the reasons, I would be annoyed:
Dog poo can be dangerous to humans, wildlife, and the environment because it can contain:
Parasites
Roundworm eggs, which can remain infectious for up to two years. Humans can become infected by accidentally ingesting the eggs or eating food contaminated with soil containing the eggs.
Bacteria
Pathogenic bacteria that can cause intestinal tract infections and diarrhea, such as:
Salmonella
E. coli
Campylobacter
Yersinia
Antibiotic-resistant bacteria