Crawlers, less so. The major search engines are getting smarter about it, but for now, you still need some kind of HTML output from the server if you really wan

Crawlers, less so. The major search engines are getting smarter about it, but for now, you still need some kind of HTML output from the server if you really want to be indexed properly. It doesn't rule out a pure client-side app at all, but you do have some extra work involved to output HTML from the server. Which is why NodeJS will ride on the coat-tails of this approach; less redundancy.