Here's why:

* Lack of Vascular Tissue: Nonvascular plants, like mosses, liverworts, and hornworts, lack specialized tissues for transporting water and nutrients throughout the plant. This limits their size and ability to grow tall, making them more susceptible to desiccation and competition for sunlight.

* Dependence on Water: They require a constant supply of water for reproduction and to absorb nutrients. They need to live in moist environments, making them less adaptable to drier terrestrial habitats.

* Limited Growth: The absence of vascular tissue restricts their ability to transport water and nutrients over long distances. As a result, they are generally small and cannot grow tall, limiting their ability to compete for resources.

Vascular plants, on the other hand, have specialized vascular tissues (xylem and phloem) that allow for efficient water and nutrient transport. This enables them:

* To grow tall: This gives them an advantage in competing for sunlight.

* To survive in drier environments: Their vascular system allows them to access water from the soil and transport it to their leaves and other tissues, making them better adapted to land.

* To develop complex structures: They can grow leaves, stems, and roots, which further enhance their survival and reproduction on land.

In summary, while nonvascular plants were some of the first organisms to colonize land, vascular plants possess features that have made them far more successful and dominant in terrestrial environments.