How the Watcher secretly doomed the Marvel Universe way back in 1966

gamesradar.com:

As anyone familiar with the Marvel Universe knows, the omniscient beings known as the Watchers are forbidden from interfering with the events of the timelines that they observe, tasked only with, well, watching and recording all of time as it unfolds around them.

However, as fans also know, Uatu, the most famous of the Watchers, has often broken this vow - most notably way back in 1966's Fantastic Four #48, in which the first arrival of Galactus on Earth prompts Uatu to aid the Fantastic Four and subtly manipulate other events to ensure that the FF can defeat Galactus and save the Earth.

But March 16's Reckoning War: The Trial of the Watcher from writer Dan Slott and artist Javier Rodriguez (which invokes the classic FF story titles 'The Trial of Reed Richards' and 'The Trial of Galactus') reveals that Uatu's interference had consequences far beyond what he and the rest of the Marvel Universe have always known, and shows that, in a way, Uatu's interference actually doomed the Marvel 616 reality.

Uatu's father Ikor and the other Watchers take Uatu prisoner over his repeated violations of his oath of non-intervention. Uatu protests his trial, saying that the Watchers must defeat the Reckoning, the eponymous villains of 'Reckoning War' who were once given advanced technology by the Watchers, which they abused for conquest. This betrayal is what led to the Watchers' cultural oath of non-interference in mortal affairs.

Uatu is strapped into a chair in the chamber where Watchers observe alt-realities (AKA the stories of What If..?) and is forced to watch the events of a reality where he never interfered with stopping Galactus, which causes Uatu's own personal reckoning as he comes to see that the Fantastic Four would have