It was probably bullshit but, in a 2001 interview in EGM (I think it was the green issue with Xbox on the cover) Microsoft claimed that the reason the Xbox didn't have DVD playback at launch was because they "Didn't want to keep the console out of the hands of a gamer" elaborating that one of the reasons the PS2 was scarce was because movie lovers were buying it.
Don't get me wrong. I'm sure the vast majority bought a PS2 for the amazing library that began from Holiday 2001 until the end of its life. The Gamecube/Xbox library couldn't even begin to compare. For that first year though, it was rough! Rather than buy a PS2 for its games, we bought one for the promise of games to come.
I think EGM said (During the launch of Dead or Alive 2) "One month after the PS2 launch and we're already back on our Dreamcasts". And when it came to the launch day "Make no mistake about it. On the day of the PS2 launch, there will be no finer game than Majora's Mask".
DVD wasn't there sole reason for PS2's success. It was just another feature in a long list of things the PS2 was doing right. Another magazine that I can't remember said "They're getting this launch so right, it isn't funny". We all know how it turned out. Not sure why the OP feels the need to defend the most successful console of all time.
