Have to consider meat digestion from a net calorie perspective. Eating raw meat is possible sure. But once you get to dense protein meats like a red meat, your body expends a lot of calories in the act of digesting it raw. Cooking it is like a pre-digestion step and allows your body to digest it with less energy expenditure.
It also probably was helpful for other reasons. You could store cooked meat easier/longer without refrigeration or kill off some of the bacteria and such making it healthier.
But the Inca lived to late for this discussion. They already had advanced agriculture. For evolutionary terms, the time before agriculture and the time of the predecessors of homo sapiens are more relevant, because that time span was larger by orders of magnitude.
When we’re capable of eating animals raw. And bugs and worms etc.
Whereas in order to consume a wider variety of plants, cooking and other more complex perpetrations are absolutely necessary.