Anecdotally, as a developer I really appreciate a well-thought-out monorepo. All the code is there. You don't have to dig around anything legacy or outdated. Searching is a breeze and it's _fast_. Updating both simple and complex logic is equally easy. You don't need to somehow discover that some other repo uses the thing you changed. Everything has the same deployment process. The tests test the thing, as soon as you push it - instead of months down the line, when someone finds forgotten repo again and oh, it's never been tested with the new functionality in our main repos. Dependency hell doesn't really exist.

There seems to be more discipline around monorepos because they're collectively owned, whereas many repos across an org each become someone's baby, and practices diverge until teams in the _same company_ fork each others' repos because they don't get along.