Microservices have nothing to do with scaling or performance,
Microservices are not just about scaling and performance but it is a core advantage. To say they have “nothing” to do with it is outright false.
Scalability isn’t something you pull out of the pocket when you need it, you must incorporate scalability by design in everything you do. (Same as with security, and testability, etc.)
Microservices are about modular design and decoupling units of code from each other. Having a bunch of pieces of code run together on a monolithic group of resources that you choose to scale vertically becomes a choice not the be-all-end-all way of doing things.
Being able to horizontally scale a service is far lower in the priority queue, and is only required once you exhaust the ability to scale vertically.
The problem with this approach is that switching from vertical to horizontal is extremely hard if you didn’t plan for it from the start. Thinking in monolithics is a very hard habit to break and it’s good odds that any platform that is steeped in verticality will be permeated by it at all levels. You can’t just come in and switch, you typically end up having to uproot and redesign a lot of things from scratch, which in most cases ends up as a non-starter from a cost perspective.