Microwave is only feasible over medium distances - can't do it over the ocean, as it requires LoS. Also IIRC, microwave bandwidth is considerably lower than fibre, and sometimes it matters.

Microwave is also affected by weather. They sometimes say that markets are slightly less efficient on rainy days. It’s a bit of a joke, but basically packet loss goes way up and they rely more on fiber links when microwave links are being shitty.