Not joking (and I know this sucks) but there are a shit ton of IE users out there still and I'm not willing to hang our product for convenience.
Vendor specific code is a reality we're going to have to live with for a long time yet.
But that's not my case, and the same goes for many others; Microsoft already got the hint on that and they are starting to catch up and adhere to standards on their latest versions and trying to get everybody to use them (it was about time).
Since there are way more teams like ours than big teams funded with huge piles of cash, we have actually managed to put the ball in their court and they cannot make us do the monkey dance as much as they used to. Can we all avoid writing vendor specific code? Maybe not unconditionally, but we are almost there.