"RISC CPUs have a choice. So e.g. smaller ARM CPUs don’t use micro-ops at all. But that also means they cannot do things such as OoO."

I don't agree with this. What do uops have anything to do with ooo execution. I can easily make a CPU with no uops doing ooo execution. Unless I'm misunderstanding and the article is just saying smaller cores don't do ooo since they are trying to stay within a certain area/power footprint.