5% would be a conservative estimate of the sites I find completely unusable on my phone for reasons that have nothing to do with Flash: text too wide and tiny to bother, centered popups that are bigger than the screen (so I can't close them), essential functionality based on mouseovers, random failures of over complicated JS/CSS, neglected mobile sites that mangle content or don't show it at all, mobile sites that break hotlinking and just take you to the home page, and so much more.
The point is, Flash is just a small part of a big problem. Web design still has whiplash from the mobile explosion. But it's going to recover real quick, and when everyone starts making mobile friendly sites, they won't be using Flash. It's on death row and Google is just dragging it out for a cheap shot at Apple.
Just grit your teeth and bear it for a little while longer. You'll have to do that anyway, with or without Flash.