This is an Accept header on IE8 with Office installed. Back when it had over 55% of market share, Google alone estimated that as much as 38Gb of useless garbage internet traffic was sent its way every single day. And that was back when the Internet population was half was it is today, web apps were were primitive, and mobile and the network constraints were nascent.
For the majority of requests I'd guess the Accept header isn't even used. Do people still write applications that send a PNG if supported, falling back to a GIF otherwise? Or use this to determine the user's language preference? I expect in most requests they are ignored and the server sends whatever it has. APIs would be the only thing I can think of, but even then you could get around that by having different endpoints for different formats. At the cost of saving a few TB (if not more) of Internet traffic a day it seems a fair trade off :-)
Accept: image/gif, image/jpeg, image/pjpeg, application/x-ms-application, application/vnd.ms-xpsdocument, application/xaml+xml, application/x-ms-xbap, application/x-shockwave-flash, application/x-silverlight-2-b2, application/x-silverlight, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, /
This is an Accept header on IE8 with Office installed. Back when it had over 55% of market share, Google alone estimated that as much as 38Gb of useless garbage internet traffic was sent its way every single day. And that was back when the Internet population was half was it is today, web apps were were primitive, and mobile and the network constraints were nascent.