Here's why:

* Alternation of Generations: Plants have a life cycle that alternates between two distinct phases: the sporophyte (diploid) and the gametophyte (haploid).

* Spore Production: The sporophyte's primary role is to undergo meiosis, a process that divides diploid cells to produce haploid spores. These spores are the starting point for the gametophyte generation.

* Gametophyte Development: The spores develop into the gametophyte, which produces gametes (sex cells) through mitosis.

* Fertilization: The gametes fuse to form a zygote, which develops into a new sporophyte, completing the cycle.

So, the sporophyte's main job is to ensure the continuation of the plant's life cycle by producing spores that develop into the next generation of gametophytes.