Well yes, I completely agree with you. That is what we should do. But each time I see more developers that leave production level apps like this. And not even small websites like http://absolutmexico.com (Has a fallback to other browsers but the developer consciously decided to not offer the same functionality for browsers other than Chrome, even after been pointed to a few plug ins that would do it for him); but also huge Frameworks, like Appian, which forces you to use IE for administration.

And there's another side of the story, in both of the above scenarios, the product/site where developed by Engineers and Web Developers. But each time, plug ins make it easier for "non-code-savy" people to implement (for example) effects on their websites that would be really complicated any other way; which is cool until the moment you notice most of those plug ins are poorly coded. The problem grows as this people sell themselves as web developers and usually charge (as freelancers) much less than the full implementation of the job would be worth. I know this happens a lot, and by a lot I mean that 85% of the independent projects I had this year were about fixing this websites or making them bigger.

I think the problem might be that, in general, we talk about all the marvels of the internet and our work with it that it just makes people want to jump in. We give tutorials, plug ins, API's, and any other tool that makes the job easier, without really pointing out all that should be needed to actually deploy to production.