In other words, no poems are written in a vacuum. Not even the first poem, spoken by some ancient person next to a prehistoric campfire, written by someone on a cave wall, or impressed in mud next to the Euphrates river, or scraped with charcoal on a banana leaf. That poem is in conversation with all other poems which have followed. Every poet is affected by other poets, and vice versa. Poets affect readers.
Readers affect poets, and so on.
More particularly, certain forms have come to be associated with particular occasions and feelings. That's what we call tradition. A good example of poetic tradition is the sonnet. The sonnet was invented by the Italian poet Petrarch some 700 years ago. So one might say the sonnet originally started off as a seduction poem.