It’s not a hard problem to notice or fix, probably just comes from people not using their site a lot. All you need to do is insert your content in a fib before a final “filler” div that has the same height as the floating footer. If your floating footer doesn’t have a fixed height (and there is some really good reason for that) a further hack is to measure it and then set the height of the filler div in js.
Also works well, but that might introduce janky behavior with iOS safari’s title bar and tapping the top to scroll to top in my experience. I don’t know if this has been fixed, it’s been a while since I wore a CSS hat, but I vaguely remember fighting with mobile safari and overflow divs a lot.