But if the requested feature is supported in a given browser even though @supports isn't, it will act as though the feature is not supported. That seems like a major flaw.
This will affect a small percentage of features, in a small percentage of browsers, of the 23% that don't support @supports (all three of which are shrinking percentages).
That coupled with the fact the features are likely to be non-functional aesthetic elements makes it a very minor flaw imo.
The only significant modern-ish browsers that don't have @supports are all versions of IE (not including Edge) and Safari 8. In Safari's case, any version of Mac OS that ran Safari 8 would have gotten a Safari 9 update. So IE 10 and 11 do present some challenges in that case, but it will be up to the developer to decide if the amount of traffic from those browsers is worth worrying about.
