The thing is, you need a massive investment in infrastructure to make it happen. But once you do, its great. You can create and deploy a new service in a few seconds. You can rewrite any individual service to be latest and greatest in an afternoon. Different teams don't have to agree on coding standards (so you don't argue about it).

But, the infrastructure cost is really high, a big chunk of what you save in development you pay in devops, and its harder to be "eventually consistant" (eg: an upgrade of your stack across the board can take 10x longer, because there's no big push that HAS to happen for a tiny piece to get the benefits).

Monolithic apps have their advantages too, and many forget it: less devops cost, easier to refactor (especially in statically typed languages: a right click -> rename will propagate through the entire app) and while its harder to upgrade the stack, once its done, your entire stack is up to date, not just parts of it being all over. Code reuse is significantly easier, too.