Why does some transactions have an excessive number of receiving addresses? Such as this transaction: 92088fe6b9d9c9db84d26481b80104f8ca566649a656b7aa3e67432b346cbf1c, which has over 5000 receiving addresses.

It is unlikely that someone would send money to that many business partners at once, let along each individual output is quite small. If that is done for privacy protection purpose, over 5000 receiving addresses is too excessive.
It is unlikely that someone would send money to that many business
  partners at once


Why? It's a mass payment for "shareholders". In this instance, the transaction you mentioned is a known payment from a pool to their miners.