Of course it matters.
For gut microbes, the human body is an ecosystem, and the diversity of the ecosystem can be an important measure of health.
Primitive tribes in the Amazon or Africa have a very high diversity index because they get their food from nature, but Amazonians don’t live longer, healthier lives than civilized people, so diversity alone is not a good measure of gut health. The distribution of good and bad bacteria, and a range of health conditions, should be taken into account.
It is very dangerous to judge a person’s health based on a single aspect.
The microbiome is a critical component of health, but it’s not the whole story.