> And their mainframes, underhyped to the extreme, that more or less still run the world.

More or less, but less and less. Many a bank, airline, etc. has had or has or will have a "digital transformation"/move to cloud/rewrite apps/websites to actually be usable/etc. project to switch away from legacy stuff handicapping them to a more modern leaner tech stack. Mostly because they got shown by newer, leaner competition how it's done (neobanks, low-cost airlines) so finally there is some incentive. And of course the added benefits of commodity hardware (as a Service) being much more easily replaceable and scalable. If you're a big bank/airline, why would you spend billions on mainframes from a single vendor you're beholden to, with all the staffing problems (nobody knows this stuff so hiring is a nightmare), specced for the highest possible load you might get? Instead of throwing it on AWS which "everyone" knows and can scale up/down based on demand. Migrating isn't easy or cheap, but it makes so much sense.