Does anyone feed their LO meat yet, puréed or otherwise?

Backstory: my MIL is a pediatric nurse practitioner so we go by her advice a lot, but this time I think she gave me BS advice. We’re feeding our 6-month-old purées, and I mentioned to her that I was going to purée some chicken for LO to try this week. My MIL said no, she’s too young for meat. When I asked why, she said “she can’t handle it, don’t give her meat until she’s closer to 9 months old.”

I can’t find any supporting evidence for this...anyone heard something similar? My LO has no allergies, no digestive problems or anything, and eats all her purées well.