This post includes recommendations for teams that are procuring websites, and I think they can be summed up as: *buy simpler problems*.
Every feature that gets added via JavaScript is more complex, more expensive, and harder to improve. That means that when things go wrong, they're treble costly to fix because JS is *"f-it! we'll do it live!"* for web development. JS disables or routes around all the ways the browsers try to help.
Let browsers help!
In this sense, progressive enhancement can be understood as *"let browsers help as much as they can, and only add what they fail to provide"*
This leads to simpler, cheaper solutions to common problems. First, because many of the problems you'll end up with are about letting the browser help *more*, and if you haven't YOLO'd your site off a bridge, that's easier to do.
Second, because you've minimized the amount of JS that might be defeating browser attempts to help in the first place.
Alex Russell