It's less about the poundage and more about your ability to pull back 80# repeatedly, with good technique, and being strong enough to do it consistently.
People love to whinge about it because we know you can kill animals with bows that are much less than 80#, so it's like people genuinely believe 80# is a complete waste.
For the most part, if someone is strong enough and has good enough technique that they can handle a heavy bow well, why not shoot it? That doesn't mean for a dozen shots in your backyard after work, either. I'm talking genuine reps, no breakdown in form, etc. I shoot a 78# compound bow consistently and easily and I'm only 5ft 7in and about 180lb myself. I've shot it at local field archery competitions where we shoot minimum 80 arrows. I do lift weights consistently.
I've seen many older and weaker people injure themselves pulling bows that are much lighter than 80# because their technique is terrible and they don't look after themselves.
A lot of the trends in the US at the moment are on either end of the spectrum - people shooting sub 450gn arrows for elk, and people preaching the super heavy arrow debate. The fact is, a lot of people like arrow speed to be at a level that helps with their longer distance shooting and reduces pin gaps. Shooting 80# can easily get you to that point with an arrow of around 500gn, so that's nice.
Of course, you don't need that much power, but it's nice to have. I've killed animals with trad bows that are less than 50# with arrows between 450-550gn plenty as well, so I'm comfortable with the idea that killing animals isn't really about speed. Having said that, I might chase water buffalo next year, so I'll be working on my compound and trad bows as heavy as I can get them. Part of building that confidence will involve shooting a lot of smaller animals in the lead up, and shooting a heavy setup with a heavier arrow definitely allows for a lot more forgiveness in shot angles.