It's possible I suppose, but three dashes already sometimes appears in GNU for hidden options and, probably more importantly, I think it would be frustrating to have to remember whether it was `--filter` or `---filter` for all long flags.
Maybe uutils could have a build feature that specifically turns off the prefix matching and will break stuff but allows using newer and more useful flags in exchange. I've VERY rarely seen prefix-matched flags being used so I'd wager a distro could be fine deploying it that way.
Ie, setup the features "gnu-compatible-opt-matching" and ship it by default, then gate the extra features behind not turning on that feature.
It's a good idea to make the prefix matching optional. I think it might be confusing to gate other features behind it though. I guess we'll get to this once we find flags that are important enough. So far, we haven't really had significant issues with this; compatibility remains our primary focus for now.
