It's not clear to me that the Internet is the best medium-- in fact, it's clear that it is not the best medium-- for long-form reflective, evaluative or detailedly analytic criticism of poetry, or of any other art form whose products are both durable and portable.
It may, though, be one of the best media for critical analyses of single works in certain performing arts, such as live rock, some jazz and small-scale serious theatre, where books and quarterlies take too long (the show's closed) and the more frequent print periodical media (e.g. newspapers, the New Yorker) have neither the column inches, nor the commercial latitude, nor, in many cases, the staff expertise to give the perfomrnace what it deserves. The Internet is going to do a lot more to change performance-based poetry, include the necessarily performance- or video-based poets of American Sign Language, than to change the kind of poems I write and (mostly) read, shortish works in alphanumeric script in Western languages, created for silent reading on the page.
The second-best thing the Internet can do for those works (shortish works in... on the page) is to make far broader, and more democratic, the discussion about those works, new and old. Silliman is pretty influential in part because he's a very good, and very readable, analyst of the kinds of poetry he likes (some of which I like too), and in part because it's pretty easy for people to find and read his analyses. We know where to look, and we know when (every morning, except when he's on vacation), and it's free.
But the very best thing the Internet can do for page-based lyric poetry is simply to make it easier to find the poems. Big archives with institutional support can do this for the poetry of the past: for the poetry of the present, it's best done by individuals or small groups of folks with recognizable tastes who put up one or two poems at a time, every day.
The very popular Poetry Daily people do this with poems accepted or published elsewhere, and they try hard both to find poems they like and to be catholic (wide-ranging, leaving-nothing-out) about their tastes: it's a big task, but in some ways it's less interesting than the task set by poem-a-day webjournals who look for previously unpublished work, since the latter are (a) unable to rely on big names when stuck, and (b) if they're doing it right, establishing an identity for themselves, as well as for their authors.
For example, No Tell Motel, where the poet of the week is Janaka Stucky, of whom I had never heard before. The No Tell folks seem to like poets with humor or sex-- ideally, both-- who write fast-moving, too-fast-to-be-narrative, free verse. There are many more poets in the archives, many of them at least somewhat talented, I'd say-- most of them at least entertaining or witty-- a few of them potentially very popular (not necessarily the ones I like!)-- and very few of them already well-known. Skip through it one day. You're going to find something you like.
Stephanie (also Steph; formerly Stephen) Burt is a poet, literary critic, and professor. In 2012, the New York Times called Burt “one of the most influential poetry critics of [her] generation.” Burt grew up around Washington, DC and earned a BA from Harvard and PhD from Yale. She has published four collections of poems: Advice...