Interestingly Meta went with a django monolith for their new app and their goal was definitely in the order of 100 million concurrent users.
Not saying it can't handle everything as well. Just saying the modularity of microservices makes it, in my pov, easier to handle large complex real time systems.
Maybe that's also something that comes with experience - as a rather "newish" guy (professional SE, so one level above Jr), it makes it easier to work on our project.