https://www.forbes.com/sites/quora/2017/03/20/why-cooked-mea...
https://www.forbes.com/sites/quora/2017/03/20/why-cooked-mea...
The classic study on this used pythons to measure the energy cost of digestion. Cooked meat was significantly cheaper to digest than uncooked meat: https://www.sciencedirect.com/science/article/pii/S109564330...
Another study on mice measured metabolic changes following a diet of cooked vs uncooked food. Again, mice did better with cooked meat than with uncooked (they lost weight on both as a pure meat diet is not a perfect food or mice, or humans for that matter): https://www.pnas.org/content/108/48/19199
Likewise for vitamin C.
The other is personal experience. Try eating tartare and then some cooked meat and compare digestion & satiety. With raw meat I reach satiety much quicker. Perhaps an experience closer to most is raw fish as sushi etc.
What kind of issues do you think would arise?