It happens for another reason too: everyone likes to flatter themselves that they're top-tier big shots, that they're "web scale," that they have the same scaling problems and uptime problems that Google and Facebook have, and thus they think they need to adopt the same architecture patterns that Google and Facebook use.

Someone builds a monolith, it gets some traction, and suddenly the server bill gets into five, six figures a month. Management have never been management before, and have never paid anything more than a few hundred dollars a month for servers, so their new cloud bill is mind blowing to them. They're spending as much money as a house costs every month on renting servers. They imagine they're hemmoraging cash right and left, they freak out and order engineering to rearchitect everything around a Service Oriented Architecture, because clearly it's time for the big boy toys. Google does it that way, so clearly that's what one does when one is at scale, when one is successful and has lots of paying customers, right?

99.9% would be better off financially and technically just rewriting a V2 of the monolith using lessons learned from V1, but that's perceived as outmoded, old-world thinking, because it's not what Google does.