That's b.s. Netscape had no involvement with the HTML WG, not even
enough to obtain a distaste. Netscapisms came about because the
developers just assumed HTML+ was dead, rather than actually asking the
author (Dave Raggett), and the Netscape developers believed they "created"
the Web and therefore were in the best position to invent new HTML.
SGML folks dominated the WG discussion because Spyglass was the only
browser folk who bothered to show up. Netscape has no one but themselves
to blame for that fiasco.