This. Remember the various 'stalking horses' that challenged various Tory and Labour leaders in recent decades. I can't even remember all their names. It was all a waste of time, a media frenzy, a distraction. The unionist media would have loved it. They scream "stitch-up" now, but if he had stood, it would have been "SNP in split".
The exception (supporting the 'healthy democracy' view) was Jeremy Corbyn who maybe stood as an outsider, but he was representing a well established tradition/position/wing of the party.
As others have said or implied, in a normal country we could support the idealism of 'healthy debate' but in a country where most parties and media are controlled from outside the country, different rules apply.