Network Load Balancing- Unicast or Multicast?

I am learning about this subject on a fundamental level in a college level course. From my understanding, Multicast makes sure that requests hit the different client servers of a system simultaneously, and allow for equalized load balancing in case of a client failure. On the other hand, Unicast is dependent on the pathing the request is sent through, so some are ahead of others as far as when the data would hit. Also, it appears they don't always have the best backup scenario in place; if a server goes down, its reliant to carry the rest of the requests on the clients that are synced with it (time speaking), and none else.

I'm just curious to hear some real world examples of when Unicast would ACTUALLY be beneficial to use, since as far as I can tell, it's the suboptimal system here...

thanks in advance!