Layer 4 load balancing can be a huge reduction in work for the load balancer; especially if it's in a Direct Server Return configuration, where the load balancer only sees incoming packets, and response packets go directly from the server.

The downside is you lose any ability to balance based on details of the application protocol, it requires some specific network setup, and it's hard to find a DSR load balancer in managed hosting or cloud. I'm not sure if there's off the shelf software to manage DSR either (the basic pieces are there in most firewalls, but management isn't)