Multiple network round-trips to find a 'good' back-end is undesirable. If your client is browser-side javascript, for example, then these can directly affect responsiveness and time to page usable.
Random is significantly easier and cheaper to implement. As you scale your service to multiple back-ends for the first time, you pragmatically start off with a random client-side load balancer - because it is cheap and simple.
Load balancing is one of those things in your product that once working to some minimum extent, nobody cares about improving. Swapping out the client side load balancer for a 'real' load balancer is the last thing on team's mind. So, you'll see a very large number of mature products continuing to use them.
Last point, random-client side load balancing provides a true solution for SPOF where as in the other methods, you still have at least on SPOF somewhere in the system.
Random is significantly easier and cheaper to implement. As you scale your service to multiple back-ends for the first time, you pragmatically start off with a random client-side load balancer - because it is cheap and simple.
Load balancing is one of those things in your product that once working to some minimum extent, nobody cares about improving. Swapping out the client side load balancer for a 'real' load balancer is the last thing on team's mind. So, you'll see a very large number of mature products continuing to use them.
Last point, random-client side load balancing provides a true solution for SPOF where as in the other methods, you still have at least on SPOF somewhere in the system.