Are we not coming full circle? Can't you make the argument that we're getting closer to a world in which all the server does is store and retrieve information, while the browser does the heavy lifting? Thank you JavaScript and web APIs.
Actually, I'd say we've gotten to the point where it usually doesn't matter who does the «heavy lifting», because CPU time is so comparatively cheap.
Would you say the same is true for, eg, the «heavy lifting» done by a Google search? I certainly wouldn't, so I don't think your statement is true in the general case, though it is certainly true for a large class of software.
I have the feeling that hard work on browser is still a bad idea.