Welcome to BR! You make some good points, but personally I just think the harsh seasons and amount of preditors make it make it very hard for a bass to grow to that size...not saying it's impossible, but there is a reason why you RARELY see a 7 come up.
When bass bite, it's not always to eat, so your notion that the bigger fish aren't being caught because they only eat at night in my opinion isn't all that accurate. Not saying they aren't harder to catch, but if there were more out there, anglers would find ways to catch them, and I have never seen an 8lbr.