Oh for sure, that’s why I mention the weight distribution. There is a difference to sitting around a horse vs sitting on it, and we know that at any weight. There’s also a fair amount of difference in body control possibilities (so someone with a wobbly middle is going to struggle more with body control) and that for sure affects the horse.
But looking at a photo, we can’t tell that is the case, because that person with the wobbly looking middle may actually have a really strong core and may be able to sit light, and the person who looks “thinner” may ride like a sack of potatoes. That’s my only issue with people judging based on photos.
I’m 5’9", and people are shocked at how much I weigh no matter my actual weight (which has fluctuated through the years), even at the nurses when every single time they have to move the stupid thing up to the next notch. I’m both blessed and cursed I’ve never had a problem finding suitable horses and have always been very careful about saddle fit etc. as a result of being tall and heavier than a similarly built person at 5’4".