Transparently self-serving, it seemed like just another hurdle, just another can-kicking exercise, risible and beneath contempt.

Once green-lighted, after a desperate High Court challenge, it provoked the gravest warnings.

It would license a hideous public discourse, applying an unfair society-wide judgment on individual identity - a cold-hearted metric devised exclusively to devalue same-sex attracted relationships.

Zero weight was given to any affirmation arising from the major party leaders backing the change, let alone that flowing from a likely victory.

And in all the indignation, it was completely lost that marriage is by definition quintessentially a social construct. The broader the social engagement in its modernisation, the greater its validity once so broadened.

Politically this has been excruciating.

There's no denying the Prime Minister lost paint in middle Australia by embracing an ostensibly "ridiculous" process. But neither can one ignore the realpolitik. Bluntly, Turnbull saw no realistic alternative if he was to drag his party into the 21st century.

Wisely, equality advocates chose to participate strongly, even as some within favoured a boycott. The temptation was to limit its turn-out to below 35 per cent and then argue its result was meaningless.

Hardheads decided to go for broke. They knew that drumming up the vote was also drumming up the survey's credibility, thus validating the Coalition.

But the bigger principle was worth protecting.

Ironically, the greatest advantage now, assuming a strong public endorsement, is the legitimacy of any question that has been so publicly and extensively litigated.

Indeed, the greatest asset the "yes" case has ahead of the parliamentary vote is that clear public endorsement.

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Denial would be betrayal on a colossal scale.

In practical terms, the survey has given Coalition MPs the cover they need to ignore their recalcitrant base and vote squarely for social justice. More than that, it brings a moral and democratic obligation.