It all comes down to coordination and regression, which are quite complex in monoliths.

Suppose you'd like to push code change to production for your monolith - how do you know that someone else's change 1) is ready to to production together with yours 2) does not affect your module. Typically these can't be answered easily - and so release process is converted to manual testing and scheduled (and often slow) releases.

I was just disagreeing with "Microservices are almost completely opposed to agile development". You can be agile in both monolith architecture and micro-services. I don't see why microservices can be opposed to agile.