Why would Pinterest acquire Jelly only to shut it down?

Because Biz is a major investor in Pinterest.
Because they wanted to hire Ben.
Because Jelly has some proprietary line of code or two that they wanted.
Because after they had all the stuff they wanted from it they didn’t see the point in paying for its upkeep.

Just a guess.

Very sensible sounding guesses. Thanks.

I read that it was an acqui-hire. As Seek said they wanted the personnel not the site.

I believe it also had to do with improving visual search, something both Jelly and Pinterest were/are working on.