Horticulture is unnatural. It involves unnatural manipulation of exotic species that were unnaturally imported from all over the World. It provides unnatural irrigation and unnatural chemical fertilizers and amendments. It involves unnatural containment of many plants within unnatural synthetic media within unnatural plastic cans or other containers. It strives to eliminate much of what is natural, such as pathogens and competition. It is ironic that so many believe that a simple but totally unnatural houseplant brings a bit of nature into their particular environment.
Nature, although quite natural, is dysfunctional. It is messy. It is dirty. It is tragic. It is potentially dangerous. It is overrated. Realistically, it is a hot mess of problems. Somehow though, it seems to be appealing.
That is why so many of us strive to incorporate more nature into our respective lifestyles by very unnatural means. We crave a sort of idealized version of what we believe nature should be. It would likely be easier and more efficient to accept such attempts as unnatural, and exclude what nature might try to contribute.
Some are quite happy to live and work in high rise homes and offices with minimal natural influence. They still breathe natural air, and appreciate natural sunlight and the stabilizing effects of natural gravity, but shelter themselves from what is most bothersome about nature outside, such as weather, wildlife and most insects.
This unfortunate old coast live oak is an exemplary victim of nature. It grew here naturally for two centuries or so. It obtained all that it needed from the natural soil, air and weather. It survived natural insect infestations, and long ago, may have survived natural forest fires. Ultimately though, perhaps in conjunction with a bit of natural wind and natural fungal organisms associated with decay, it succumbed to natural gravity.