display: contents does not have widespread support yet. I imagine once it is widely supported, it will be used quite frequently. As such, it is logical that there exists an element that defaults to it, the same was
<div> default to
display: inline and
display: block respectively.
What I’m proposing is essentially the equivalent of
<div>. I’m not sure what the name should be ─ my initial thought was
<contents>, but that was previously used. However, it would not be unprecedented to deprecate and element and later reimplement it (I can’t recall the element, but this has happened once before).
Hopefully this will receive some consideration.