yea we don't live that way of life anymore. We are talking about running for fitness after sitting in front of a computer for the rest of the day.
If it is so natural why do we need to read books and blogs about form? Are you suggesting that prehistoric people went through "running form bootcamps" before making it their "way of life" ?
The reason why we need to read books and get interested in the theory is especially because we're culturally evolved in a way that doesn't require for us to run around all day long. The skills associated with running are now almost obsolete when they were absolutely crucial back in the days of hunting and foraging for food. As a result, we've kind of lost touch with the minute details of what makes for efficient running, just like I'm not sure a lot of people would know how to make a fire in the wild anymore, those activities are a bonus now, not a necessity.
So you don't tend to see animals running for hours because that's a human speciality (among predators), and it's part of why we've been so successful as a species, despite our physical weakness compared to other predators.
And the reason people need technique bootcamp is they're not physically active anymore. They have muscular imbalances that need direct attention to correct.