Xに 配られた = Distribute by/to X?


I came across this sentence on
[Tatoeba](https://tatoeba.org/en/sentences/show/145321):

> 新しい毛布が貧民に配られた。  
>  New blankets were distributed to the poor.

My question is, why doesn't this mean "distributed **by** the poor"? Why
doesn't に here specify the agent with the passive verb 配られる?

