I do the opposite, I optimize for Safari/Firefox. Chrome with it's market share and pushing own features seems to be better analogy for IE.
In the early days maybe with ActiveX and friends but that was a small portion of IE's life. The vast majority it remained a laggard until Edge and now the Blink switch.
Safari is usually the last one to the party and often has the most lolwtfbbq bugs which to me was the essence of the IE6+ era.
Nnno, Chrome is the new IE5 of this era: putting stuff in unilaterally without regard to standardization and pushing webdevs to see Chrome as "the standard".
There's a 6 step process to shipping features, which includes writing specs, seeking guidance from others, asking for W3C Technical Architecture Group & security group review, & numerous phases of soliciting comments. https://www.chromium.org/blink/launching-features/
Can you name a piece of software that does a better job about being open, transparent, & working in a more pro-social way?
Also Blink based browsers have vastly more market share and generally if it works on Blink it will work on Firefox/Gecko, because unlike Safari/Webkit it doesn't live in the dark ages.
The only reason people don't outright ignore it is that it's the only engine that runs on iOS. This does often mean though people only test for it when doing mobile/responsive testing.
Apple either needs to really get off their ass and invest properly in Webkit or do something more drastic like adopt Blink (bad for us, browser monoculture but probably easiest option) or Gecko (good for us, unlikely to happen).