Folks know Langston Hughes's "Mother to Son" and "The Negro Speaks of Rivers." They know Gwendolyn Brooks's "We Real Cool," Robert Hayden's "Those Winter Sundays," and Margaret Walker's "For My People." But, fewer people know the specific volumes of poetry by those poets where those individual poems appeared in the context of several other works.
Contemporary poets are often known by their volumes of poetry, especially award-winning books. So large numbers of people are aware of Terrance Hayes's Lighthead, which won the National Book Award for Poetry in 2010, Nikky Finney's Head Off & Split, which one the award in 2011, and Tracy K. Smith's Life on Mars, which won the Pulitzer Prize for Poetry in 2012. Far less people can identify specific poems from those volumes and the volumes of other award-winning contemporary volumes.
Apparently, canonical poets are known by individual poems, while contemporary poets are often recognized for their books. The expanded system of anthologies are largely responsible for making canonical poems and poets canonical. Folks know "We Real Cool" in large part because they have encountered it in so many anthologies.
Contemporary poets, by contrast, are less likely to have their individual poems repeatedly reprinted in modern-day anthologies. Some of the poets, however, win prestigious awards, which can bring them more publicity, increased book sales, more speaking gigs, extended notice for their award-winning book, and future book contracts. It's that initial assortment of poems in the book, not a single one, that becomes the passport for recognition.
Since anthologies remain crucial portals into larger realms of poetry or as gateways into the works of a single poet, the appearance of individual poems in collections will continue to serve an important purpose. At the same time, there is some worry that the poets will be limited to a few select pieces. By contrast, award-winning contemporary poets or poets whose books become popular will enjoy the advantage of readers taking a look at and appreciating several of their poems at a time. On the other hand, it's less likely that many "new" poets will gain attention in classrooms across the country and across generations by having a body of their works presented in anthologies.