Simple answer: Don Cherry.
For years, Cherry was showing that play on 'Hockey Night in Canada', and always talking about Orr scoring while flying through the air after being tripped. It was pointed out several times that he scored, then jumped afterwards. Finally, Cherry stopped lying about it, and for a while stopped showing it all the time.
Orr was a great player, but he also arrived at a time when the league had just doubled in size, the WHA was starting, and coaches were just beginning to let defencemen carry the puck. (Toe Blake told Doug Harvey, another great skating defenceman, that he would be fined every time he carried the puck across centre.) Orr was a large part of the team that won a couple of cups for Cherry, and Don has been telling everyone that Orr is the greatest player of all time ever since.
Bossy just never had the PR man that Bobby did.