This is a very short sighted decision, apart from technical demo, designing a website to only work with a specific browser is actually costly, doesn't last and significantly limits your reach.
It's 2017, the era of evergreen browsers and living standards. As much as you or I may wish otherwise, anything built for the web today may not last and may have significantly limited reach within a matter of months. Every major browser developer has shown a willingness to cut off established functionality, even things that have worked for many years, if its suits their purposes. (Either that or they've abandoned older, non-evergreen browsers more or less completely.) The only standards that matter in web development today are the de facto standards of what the browsers actually do, just like the bad old days of IE vs. Netscape.
As I said before, this might well be bad for the long term future of the World Wide Web as a resource for society, but in this business you have to play the hand you're dealt, and the browser developers hold all the important cards.
