So you like being lazy ... a technical challenge comes your way and you hope others fix it for you.
This is the hipster frontend engineer attitude. Not to be mistakened for real frontend engineers who create robust sites for paying customers. Enjoy your world and ill enjoy the enterprise dollars. I like coding. I dont complain about the challenge.
For all you know, they build websites or applications that don't have any need to run on older browsers, or at the very least, there are diminishing returns.
There's always an opportunity cost. While you're building support for older browsers, they could be adding valuable functionality to their software.