This looked like a pretty long list of unsupported APIs, so I decided to do some research:
- CSS motion path is not an official standard; it is implemented only in Blink (Chrome/Opera).
- CSS device adaptation is a W3C working draft. It is available prefixed in IE/Edge and Opera Mini, but is unprefixed in 0% of shipping browsers.
- Client Hints: DPR, Width, Viewport-Width is an IETF working draft implemented only in Blink (Chrome/Opera).
- inputmode is supported in 0% of shipping browsers.
- MediaRecorder API is a W3C working draft supported in Blink (Chrome/Opera) and Firefox but not IE/Edge or Safari.
- Network Information API is not an official standard; it is supported only in Chrome for Android.
(Source: caniuse.com)
I stopped going through the list at this point. At least from the top of your list, none of these features are "shipped in every other browser" and some are shipped in no browsers at all. I'm not sure how it shows that Safari is "far behind the times."
If anything, the list seems to show that Chrome implements many non-standard APIs not available elsewhere. Combined with its mindshare (if not marketshare), this suggests that Chrome--not Safari--is in some ways the new IE6.