You can dispute whether it's a reasonable claim or not, but MS has established a reputation for revealing too early, delays, cancelling games, or releasing broken ones. This is relatively common sentiment, which if you've spent your fair share of time here and on Reddit, you would have seen numerous times.
And your examples are fairly flimsy. God of War was shown ~21 months before release, and ultimately came out as one of the best reviewed titles of this generation. Spiderman was ~14 months. And Last Guardian which I'll give you, was a passion project that many had given up hope on, and believed it buried with the PS3 generation. Nothing is as egregious as MS 2014 E3, where Scalebound, Crackdown 3, and Phantom Dust all closed the show - two of which have been cancelled, and the other is only just releasing almost 5 years later in 2019.
I really like Xbox, and delight in their ecosystem and conferences. But there's reason for the stigma, and I think it's easy enough to see why this narrative about Xbox has spread.