Why couldn't they make Joshua-Fury prior to Usyk-Joshua?

Usyk did not beat AJ till September of 2021.

2016, 2017, 2018, 2019, 2020 and even 2021.

Joshua-Fury would have been the biggest fight in boxing history. Yet they were both content to fight...

Why couldn't they make Joshua-Fury prior to Usyk-Joshua?