Why should OpenFreeMapbuild, a free public service with no SLAs, build their solutions based on what's optimal for an e-commerce site to retain customer instead of what's optimal for their project's needs? Some clients can afford to lose connectivity during an active outage, not everyone is the worst case. My web service using round-robin DNS is not an ecommerce site either, the users have already paid by the time they are using it and none have ever filed a ticket or noted a complaint in the service review about the failover being slow or unreliable so why should I build it different just because some other use case could theoretically be losing a customer during an active outage?
Running load balancers does have a downside, every single design choice other than "don't do anything" is another point of configuration and cost. Round-robin based DNS solutions often require nothing more than adding a second A record and are possible the simplest solution to many problems for that reason. Many cloud DNS systems offer automatic pullout functionality if that's even a need, keeping cases where pullout is a must still not needing to move to more complex answers.
Solutions only make sense in context of what service one is delivering, not in what thinks sounds sexiest, what is the absolute best, or what could be a possible problem in some other use case. That you can think of a case it could possibly not work out is not the same thing as an example of why it's a bad design for everyone - or even that scenario. If you can't gather data the answer is to find a way to do so and make a data driven decision, not swag based on personal opinion. Not every app is only correctly scoped when resources are put in to make it a fluid 144 FPS native experience in <1 MB package, not every DC needs 2n redundancy to be up enough for its customers, not every database needs to be designed to scale to a billion users, and not every web service needs a load balancer to be reliable enough for the use case.
