What's wrong with that paradigm? If you believe that your technology or philosophy is better than the status quo, why wouldn't you argue for that? Why wouldn't you want to convince others to do the same? The progress of the world demands on the spreading of good ideas.

Also, there are still many, many, many more PHP and Java developers and shops out there than there are Rails. That shift is far from done.

Once the good ideas have become mainstream, the work on those are done, but by then I'm sure even better ideas are available and the process starts anew.

This is not bad, this is healthy.