Part of the reason it matters more to web developers is that often our clients and employers do care what we use and if we love a particular tool it needs widespread adoption to be able to use it on real work. I have potential clients asking constantly if I can build their project with WordPress or Rails or Drupal or Symphony or whatever else they think is the best. It would be much better if they just came and asked if I could build it and let me help them determine what is the best platform for their project and pre-existing skill set.

Now, sometimes, they have a legitimate need to have it integrate with a larger system and using that tool has external advantages. But most of the time it is just a vague notion that if it is in WordPress it will be easy to use, cause you know, anyone can edit a WordPress site. But when you bolt a hundred plugins and custom business logic into WordPress, it makes no difference that it has any easy blog editor. That should have been a separate project to begin with. Half the time they have built 10% of what they need with a dozen plugins, think they are 90% done and that I can just make the rest of it work. This because someone told them there were plugins that could do everything they needed in WordPress and with WordPress they'd get good SEO.

The point is that if we want to use a particular tool, we better evangelize for it, because clients never want something built in a framework they haven't heard of. It's not even irrational for the clients, since 50% of the time their developers disappear before the project is done and they have to find someone else who can pick it up and finish.