For the example above, I would personally throw a lot more of that stuff into my check bag, if my check bag was only at 50lbs. 55lbs seems like a lot for a carry on. For your carry on bag, you are not limited by weight, however, you ARE limited by size. Your bag needs to fit into a bin of a certain size. (and then a laptop, that doesn’t count towards that).
But yes, you can bring more than 75lbs, if you know how to pack right (if it’s an issue, put heavy small stuff in your carry-on…. and leave the big light stuff in your check in bag)
Z