October's a tricky one because the last week is generally not as bad, but early to mid Oct has gotten downright crazy, esp. the week of Indigenous Peoples Day. Years of the internet beating the drum about October being slow, a pair of extremely popular seasonal events, (Food & Wine and MNSSHP), and an increase in fall school breaks I think made October more desirable.
Demonstrably untrue. This is a fallacy that's repeated online a lot but has no basis in actual fact. There are fewer slow times than there once were, but they still exist--they're just not the same ones as in years past, and the ebbs and lows are a bit harder to predict. May is still generally dead (this year was the busiest I've ever seen it during Memorial week, but I think that was down to Epic's rising tide lifting the Disney attendance boat too). And summer in general has not seen consistently peak crowds since before covid. There's a lot of factors behind that, but mainly a combo of weather and higher tickets and rack rates. Disney offering so many aggressive discounts for this time frame is for a reason, and it's not because it's busy.
The bit about party season is correct, though.