Un-prefixed declarations are everywhere. They're part of every framework, and what every developer tries first. Then comes -webkit, -o, -moz. IE hacks are far more widespread. filter?
I've been looking for sites without un-prefixed declarations for an hour and come up short. If there is any merit to this, I'd love to hear it.
* IRC log of W3's meeting, where Mozilla, Opera, and Microsoft bring up the possibility of being forced to support -webkit prefixes: http://lists.w3.org/Archives/Public/www-style/2012Feb/0313.h...
* Article on Opera and -webkit prefix adoption: http://www.netmagazine.com/news/opera-confirms-webkit-prefix...
* Mozilla's analysis of -webkit usage on the web: https://bugzilla.mozilla.org/show_bug.cgi?id=708406 There's a lot of data there. Raw data is here: https://bug708406.bugzilla.mozilla.org/attachment.cgi?id=601... . Some processed data in a spreadsheet: https://bugzilla.mozilla.org/attachment.cgi?id=599084 . You may want to view others as well.
I haven't personally looked for sites that do this, but I use Firefox and have a Windows Phone, and in both cases I have found that I've ran into sites that were either Chrome only or simply looked terrible in my browser, not because of technical limitations, but because the developers had really only tested on Chrome. In some cases, I've ended up spoofing Chrome's UA in Firefox and found that sites still worked.