According to various player reports, the lack of scaling makes open-world content above level 75 easy and grants less experience/worse loot, which is why you should complete open-world activities including Renown, Strongholds, and Legion events before you hit said cap.
Reddit user Nosism123 brought this up in a thread claiming it’s not worth completing the content above not just due to the lack of challenge or experience, but also bad loot which has a low item power when killing Level 75+ enemies.
Fortunately, Helltides and World Bosses are exempt from this lack of scaling.
PSA: Complete all open world content you intend to do by level 75. Lack of scaling ruins it.
by u/Nosism123 in diablo4