Legos were among our favorite toys for me and my (6!) siblings. Sure we had a lot of arguments back then about who would get such and such rare pieces. But conflicts between young siblings rarely last long: we would always bargain, negotiate or cheat our way out of status quo and just continue building and playing. That's just what children do.
The author may have felt very smart removing legos altogether from those children and have them discuss about privileges and feelings instead. Sadly, inequalities and conflicts are extremely valuable things for kids to experience (to a reasonable extent of course) if only just for the fact that this is what they'll find outside.
By depriving those kids of situations where they could argue and work out settlements by themselves, and instead expecting them to behave like small adults able to come up with rationals about their supposed privilege or parrot the dominant mantra, you're undermining their ability to tackle real life, to learn how to become fair (and not naive) by themselves.
Sure kids need supervision. But give them too much of it and you'll be doing them a big disservice later.