Answer:
Short Answer: It allowed them to criticize someone other than themselves
Step-by-step explanation:
When people feel bad about themselves, they have a tendency to deflect blame onto someone else. It's common human nature. Another reason is that Maycomb functions much like an echo chamber, so any pervading gossip from Stephanie Crawford, despite her reputation, spreads like wildfire, and in Boo's case not much is known about him so he is easily rejected and criticized by the town in general. As you get further into the book, you'll encounter a certain "drunkard" and a black man who face the same fate as Boo Radley.