But the Yahoo crew have taken it a step further to realise:
Support does not mean that everybody gets the same thing. Expecting two users using different browser software to have an identical experience fails to embrace or acknowledge the heterogeneous essence of the Web. In fact, requiring the same experience for all users creates a barrier to participation. Availability and accessibility of content should be our key priority.
Which is pretty obvious when you think about it. Why should we expect everyone to get the same pixel-perfect website? And the more complex a website is, the more likely it is that it will not work as expected for someone. So, they factor that into the design and development of their sites. The aim is not to say “You have a good enough browser, come on in” or “You have a rubbish browser, be cast out into the dark and cold”, but to provide a workable experience for all, but only give the full bells-and-whistles to browsers that will fully support it.