I agree with this. I've had many dozens of broodies through the years, and almost all made good moms beginning with their very first clutch. However, I've had two first-time broodies that killed their first-hatched chicks. Both times I also had other broodies due to hatch, so I pulled the remaining eggs from the "bad moms." Both bad moms seemed very distressed and confused, so the next year I gave both another chance. The second time they hatched chicks, both were excellent moms and never again hurt their chicks. I think it's possible that sometimes a first-time mom doesn't know what to think about the wet-looking rat-like thing that emerged from their nice warm egg. It's also true that some broodies Will kill chicks, so definitely watch your broody closely if you decide to give her a chance. Or, raise these chicks yourself and give her a chance next time if you choose.
Just an FYI, I did bring my current broody, a black Australorp named Ruffles, inside today for the duration of the current extreme heat wave, which should break by this weekend. Her comb was pale and she was panting in her nest box this morn, and I didn't want to take any chance of losing her. I lost a broody Welsummer sitting on eggs si0x summers ago in similiar temps as today/this week, and I still feel sad. Follow your intuition when it comes to caring for chickens; it won't lead you astray. That goes for your possible "bad mom" too!