It seems like my takeaway is identical to the article's takeaway, that getting in matters more than going. Unless you're thinking of something else.

The whole "matters less multiple years into career" bit is a cope if it's just a measure of how inherently good you are if you can get in. There seems to be a clear separation between the people that get in and the people that don't!

Good students will do well wherever they go. The “getting in” qualification is a red herring. In this case it serves as the control.