The other side of this coin is that, as a result of having evolved specific strategies to live in our dry conditions, some local native plants may not do well in other types of environments; for example, where there is a lot of water, like the typical garden. As a result, some of our local native plants may not mix well with exotic garden plants that need regular watering. They also may not do well next to lawns. Thus as in (1) above, there would be a limitation on the kinds of plants to choose from based on a plant's water needs. Of course, this would only be a problem if you wanted to include non-natives in your garden.
In any case, this limitation can be mitigated by dividing the whole garden into different planting areas based on plants' differing water requirements. Putting sufficient space between two areas, like a pathway or an open space, allows you to have both an area of native plants and, for example, a vegetable garden which requires fertilizer and a lot of water.