Scale? At what "scale" runs Linux, perhaps the most well known monolith software ever?

(And also the subject of perhaps the most well studied flamew^Wdiscussion about mono- versus microservice architecture.)

It only runs most of all servers and most of all the mobile terminals in the world. Where is that distant higher end, where microservices unlock colossal scale, exactly?

Architecture matters. Just not always the way you think. But it serves as catnip for everyone who loves a good debate. Anyone who gets tired of writing code can always make a good living writing about software architecture. And good for them. There's a certain artistry to it, and they have diagrams and everything.