The Celtics could have made 5 straight Finals if KG hadn't gotten hurt in 2009 and Bron hadn't taken them out in 2011 and 2012. How does that change them being a superteam in 2008?
Hell, if KG or KP doesn't get hurt in 2009 and 2010, or if Ray doesn't make that shot in 2013, the Celtics could have ended up with more titles than LeBron's Heat did. But that doesn't matter cause they just move the goalposts to whatever works in the moment.
The LeBron-Kyrie Cavs and LeBron-AD Lakers only won one title yet posters here call them superteams all the time.
That's one "what if", but of course the Celtics losing KG completely in 2009 and losing Perkins when up 3-2 in 2010 are stronger "what ifs" than Pau getting a few extra games to build chemistry.
The Shaq-Kobe-Malone-Payton Lakers were definitely called a superteam in real time. The Celtics were too. But you're right that it wasn't until Bron did it that the media really jumped in with the hate and tried to make it into a huge negative before they'd even played a game.