I think the problem is punctuation; reading that sentence it looks like "Web frameworks [that] are no longer supported[.] In JavaScript we have seen Backbone, k

I think the problem is punctuation; reading that sentence it looks like "Web frameworks [that] are no longer supported[.] In JavaScript we have seen Backbone, knockout, angular, ember, and react in rapid succession..." Which is a true statement, though you're right that it looks as though the implication is that they're no longer supported when in fact it's simply that the older frameworks are losing momentum and mindshare.