It's not stupid. From an academic perspective, sure it works either way. From a business perspective, you have to support the full feature set on a given set of

It's not stupid. From an academic perspective, sure it works either way. From a business perspective, you have to support the full feature set on a given set of browsers, and you're not going to waste time on a solution that only covers 80% of your required browsers when you can write one codebase that covers all of your browsers.