You're asking a really good question, but if you'll may I think you're asking the wrong one. To answer your question, why shouldn't your browser support quick

You're asking a really good question, but if you'll may I think you're asking the wrong one. To answer your question, why shouldn't your browser support quick and easy viewing of PDF files, I think the answer is that my browser's job is to render HTML downloaded over a given protocol (such as HTTP or HTTPS) and appropriately supported non-plugin extras as best as possible. For example, I have a virtual world. This virtual world is designed for a niche, lets say vehicle mechanics. You can look at any vehicle and strip it down or away to see each layer like an onion skin in my world. Why should your browser do that instead of giving it over to a plugin by the format company's author? If your browser does that the people that write the browser have to support it to a certain extent - if they implement the popen() function in the spec, well they're importing the standard into the browser but if popen("/bin/ls") works then so should popen("/bin/ls;cat%20/etc/passwd"). My point is that the people that make browsers make really great browsers, the people that make PDF readers make great PDF readers. To pull the browser guys off to make a PDF reader is the same as pulling a PDF reader guy to make a browser, it's not their core business. I'd rather trust a company for whom PDF reading is core business (like sumatra) than those that feel PDF reading is only part of their revenue stream (like adobe).