Why we need multiple discovery services engine?

From: Wayne Lam <wingsss_at_nyob> Date: Fri, 1 Feb 2013 10:31:51 +0800 To: CODE4LIB_at_LISTSERV.ND.EDU

Hi all,

I saw in numerous of library website, many of them would have their own
based discovery services (e.g. blacklight / vufind) and at the same time
they will have vendor based discovery services (e.g. EDS / Primo / Summon).
Instead of having to maintain 2 separate system, why not put everything
into just one? Any special reason or concern?

Best

Wayne