Was it though? At a minimum i think a "standard" is a document detailing the behaviour of at least two competiting implementations sufficiently that you could use it to make a new implementation that was interopable. I don't think that was true of W3C standards in the pre WHATWG days. Compare it to say the HTTP rfcs, which i think did meet that standard.
Opera would be a good example of a third independent implementation successfully competing with the primary two (IE and NN/Mozilla). I remember switching browsers back and forth several times back then - I was an Opera 6 user, then moved to Firebird/Firefox shortly after it was released, then back to Opera 7/8/9, then to Chrome.
It was a fairly brief period, unfortunately - roughly between IE losing definitive market dominance, and Chrome acquiring the same.
Was it though? At a minimum i think a "standard" is a document detailing the behaviour of at least two competiting implementations sufficiently that you could use it to make a new implementation that was interopable. I don't think that was true of W3C standards in the pre WHATWG days. Compare it to say the HTTP rfcs, which i think did meet that standard.