If it works on Chrome, no one cares or even tests for other things.
If there is a JS feature in Chrome they want to use, so it’s impossible to use other browsers (instead of looking wrong) people do it.
Performs fine in Chrome? Ship it.
Yes, Chrome is the new IE in that it’s the only browsers companies care about, just like IE was for a very long time.
Everything has to be Chrome compatible to succeed. That’s the benchmark, not what the spec says.
We've been through an extensive standardization pass for this to not happen. Anything not matching the specification whether in Chrome or any other browser should be considered a bug.
This is not at all the same as IE, where it just went its own way.
This latter bit isn't in conflict with the standard; it's an essential part of the standardization process. The typical route for something making it into the standard is for a browser to release their own browser-specific extension and use that as a basis for advocating that it be added to the standard. XMLHttpRequest, for example, started as an IE-only feature and didn't make it into all the other major browsers for several years. It got a published W3C spec a little bit after that, which meant that browsers needed another couple years to also get synced up on their behavior.
In this respect, Chrome has definitely now taken IE's old position: new Web standards have a tendency to start as Chrome-specific extensions, and then the other browsers have to implement their own versions and get them ratified into the W3C specs in an effort to try and keep up. Which in turn suggests that a compatibility-minded Web developer might want to choose a similar strategy from what was done in the past: test on the most popular browser last.
Sure, but there is a big difference between implenting 99% of the standard and only implementing like 10%
But if developers don't check, then either one could break the site for all the users.