[chriswarbo]

This is definitely true, given how often I've had my keyboard become unresponsive, only to find out that some little Flash widget had the focus and completely bypassed the browser, requiring me to use the pointer to click on some (hopefully) empty area of the page.

I will say that Flash isn't usually required for most of these uses; just like Javascript it should degrade gracefully to a fallback (eg. a POST form for uploads). Except for web sockets, if they're powering something fundamental (which is the same for JS).

The only time I've added a Flash widget to a page without a fallback has been "copy to clipboard" buttons, which didn't have a decent alternative. In those cases the button just doesn't show at all.