I think it has more to do with &quot;old&quot; IE11 version on Windows&lt;10: See <a href="http:&#x2F;&#x2F;caniuse.com&#x2F;#search=http%2F2" rel="nofollow">http:&#x2F;&#x2F;caniuse.com&#x2F;#search=http%2F2</a> vs. <a href="http:&#x2F;&#x2F;caniuse.com&#x2F;#search=spdy" rel="nofollow">http:&#x2F;&#x2F;caniuse.com&#x2F;#search=spdy</a><p>A awful lot of companies still use IE and not Windows 10 ;)