I do not disagree with your sentiment but the cold hard fact is that this coverage is often prohibitively expensive. A compromise needs to made somewhere and a proper understanding of your audience will help to inform where that compromise is made.

There are lots of opportunities to create great experiences for specific mobile platforms and there’s plenty of room for web, native, hybrid, and whatever solutions. (http://bradfrostweb.com/blog/notes/native-vs-web-is-total-bullshit/). But when it comes to the web, it’s important to encourage and embrace its inherent inclusiveness. Stephanie Rieger beautifully stated “Diversity is not a bug…it’s an opportunity.” (http://stephanierieger.com/diversity-is-not-a-bug/), and to capitalize on this is good for users, good for business, and good for the web.

Now back to reality. The fact of the matter is that there’s no possible way to test on every device, platform and configuration on the planet. That’s why it’s important to understand the difference between ‘support’ and ‘optimization’ (http://bradfrostweb.com/blog/mobile/support-vs-optimization/). It’s our job to educate clients and team members that we can optimize for the platforms that make the most sense for particular project, while simultaneously providing support to the myriad of other connected devices both present and future. So while it might not make sense to make sense to bend over backwards for Blackberry 4.2 users in 2012, those users should still be able to be able to access one of mankind’s greatest achievements.