It is not more "outside the Unix philosophy" than most of Unix these
days to have something other than the old `find | ...' do tree
traversal.  But enough of the Unix philosophy is still intact to
implement it in the shell rather than in `grep' or in some bizarre
instrinsic way in the system.  I believe `zsh' has some
tree-traversing globbing constructs; people who want a kitchen sink
command line should use the kitchen sink shell.