Interestingly, the Princeton Encyclopedia of Poetry & Poetics does not define poetics as the discourse of poets about poetry. The section on "Western Poetics" for example, when it gets to modernism, talks only about literary theory. Modern poetics goes from Croce to Russian formalism to Anglo-American New Criticism, with a brief detour through a series of writers taken to be critical of Croce's expressionism or of Western presumptions of universality generally. This is just bizarre. You would think Ezra Pound would be mentioned somewhere.
It is only at the end that poetics is defined as "the compositional principles that poets themselves discover and apply during the writing process" (1064). This seems only the case for "Postmodernism and Beyond," though (according to this article). This seems like a very narrow definition, too. Poetics is not just discovered and applied "during the writing process." As I see it, it is a kind of "poetry by other means." It could be the internal poetics inferred from reading poetry, an explicitly metapoetic "ars poetica," prose writing set apart from poetry, or hybrid works of prose and poetry like Spring & All.
Poetics, in the preface to the entire volume, is defined as "the theoretical and practical study of poetry."
From one point of view it doesn't matter whether Charles Olson or Roman Jakobson is doing poetics. It is still a theoretical and or discourse around poetry. There is, however, a specific tradition of poets doing poetics, and this tradition does have a certain continuity that is lost by subsuming poetics to literary theory ("about" poetry).