@christopherv Coming from a similar background and getting inconclusive answers, it seems all intuitive for what works and what doesn't work. I'll see if I can somehow organize my thoughts for these last few months.
So I've been plant-based since the start of the new year, and prior to this I would range from 0.8g/lb-1.25g/lb of protein. I was pretty anal about hitting my protein. I've read research and other subreddit/forums about not needing much protein relative to fitness community (~0.6 g range, which for anyone in fitness community will seem very low), and it made sense because you only readily lose muscle going on a cut or going a full sedentary lifestyle. I know high proteins is advocated in the fitness community as sound advice because it makes cutting much more easier.
Going plant-based, I've been hitting about 0.6 g/lb to 0.8g/lb, and I've been getting stronger, especially considering I've been lifting for several years now. I was reading that some ranges like 0.64g/lb-0.8g/lb tend to be more adequate. I'm also on a lean bulk, so all those carbs help with that. I'm going to be going on a cut soon, so I'll be playing around with these ranges and see how I feel.
TL;DR: I feel high protein in fitness industry is because of bodybuilders on steriods can make use of high protein diet, and it's easier for fitness purposes, not necessarily life purposes