"Works in Chrome" is definitely becoming the new "Works in IE" unfortunately. If you check the /r/firefox subreddit, there's usually a post crying about how a site only works in Chrome which is frustrating. [0]
Yeah there's definitely sites that flat out don't work in Firefox for no good reason. If you're intentionally breaking your site in this day and age I probably don't want to actually visit your site. Oddly enough I've jumped back to IE a few times to get some banking sites working.