The author mentions that movies by new directors that were hit were
backed by strong personalities. Lagaan was produced by Aamir Khan.
Rakeysh Mehra himself admits that without Aamir the movie was not
possible, hence again the movie had strong backing.
As I don't watch Tamil movies I can't comment on them.
However, i'd say that a good script rendered badly on screen can also
spoil a movie. But with the kind of movies being churned out of
Bollywood, ARR's choice seems spot on, with a few exceptions obviously
like Lakeer, Kisna. But I'm glad he did compose music for them!
So an interesting observation indeed!