When I was bulked up (and fat) it was much easier to squat heavier, that extra mass around my core , glutes and hamstrings helped, even if it was just extra fat.
One of my friends who is very strong powerlifter [not by world record standards - but benching around 500, and deadlifting/squatting around 800], who then decided to cut up and look more like a bodybuilder [non-pro] said that his deadlift went up when he lost weight, because he was able to get a better starting position with the barbell and his feet/leg placement.
He said that his squat went down though, for the same reasons why you mentioned - he specifically said that he lost mass/fat in his glutes and hamstrings, where he was previously able to "bounce" off his bigger/fatter hamstrings.
Someone also told me that if you have a big stomach, you can also sort of use it to "bounce" up from a squat.
It's interesting to think that fat would make a person stronger...but it does.
In strongman training, I have some difficulty with Atlas Stones [I can load the 250-lb stone to a 50" bar, but not the 300-lb stone] because I have no big stomach to rest the stone on during the lift. I also struggle with the Axle clean and press for the same reason - I have no stomach to hold/bounce the bar off.
Early in my lifting career, I would have never guessed that being fatter can help a person lift more / be stronger - but...yep. It sure can, for the reasons outlined above, as well as others.
