Amazing ... but there is a reason.
He played for 2 teams only, the Raptors and the Hornets (after an early stint with the Rockets) and after 2008 he never had a team around him that was strong enough to go the distance. What he was missing mostly was a strong 2nd scoring option and enough good role players, as he only had either. And regular season success is worthless when individual matchups dictate the playoff series.
Look at his chances for a title by periods:
The early Raptors years probably were his best team and title chance as the Raptors dominated the league and 2 stunning playoff defeats (including the memorable 1st round defeat from Okur and the Bucks) that lead to the Raptors breakup. They never won more than 46 games afterwards anymore and even missed the playoffs when teamed with 26ppg scorer Hoffa (but the rest of the team: yikes).
On the late Raptors later he was surrounded by mostly youth who simply wasn't there at that time.
With the Hornets he was the only offense early, missing a top 2nd scoring options as most title teams had. And while the defense was always top the Hornets simply ran into opponents - mostly the dynasty Nets - with deeper offense in decisive playoff series. Still, on the 2013 Hornets he came as close as you can get, one win away from the title (before another stunning collapse followed)
TMac came way too late as his better years are long gone now.
In my view Yao had two realistic chances for a title:
the 2007/08 Raptors teams with Peja, Mihm, B-diddy, Cato (and youth like Sedran, Springs, Lovelette and Schenk) ... they broke up WAY too early. Only Cato was older than 29 and they could (and should) have won a couple of titles later.
And of course when he finally overcame the arch rival Nets and took the Hornets within one game ...
But of course, it's not over. Put him on a veteran team like the Celtics now. Would you honestly bet against Yao-Dirk-Marion ?