Kamin Asks Why SSRN Hasn't Displaced Law Reviews

Over at Prawfs, Sam Kamin asks why legal academics continue to publish in law reviews.  It seems to me that there are several reasons:

• One is that SSRN is not institutionally well suited for the role of permanent repository.  SSRN is actually a relatively small private organization that does not, so far as I can tell, have a continuity plan for its archives in case the organization should go out of existence.
• Another has to do with the comparative advantages of Westlaw and Lexis as search engines.  Google is great, but Google does not permit the full range of proximity operators available from Westlaw & Lexis.  Moreover, Westlaw & Lexis focus research on texts likely to be relevant, whereas Google generates considerable noise.
• Of course, there is also a certification function--law review placement inexcplicably confers certification (although this seems quite mysterious given the relative inexperience of the selectors).

There are surely many other reasons as well.