> Let’s say I want to run something open-source in my AWS account; call it MySQL for this thought experiment. I can set up MySQL on an EC2 instance, or I can use AWS’s own managed service (in this case, RDS) to do it for me. I’ll pay slightly more for RDS, but that’s fair; there’s value in having AWS’s operational expertise applied to running infrastructure for me.

The author acknowledges they know they are already paying a premium for the managed service. With that premium you are also paying for the traffic between instances. If the price was the same I'd see how this is anti-competitive but like this I don't understand the argument.