This is a request for further enlightenment.

Since bless returns the blessed object, is there anything actually wrong with blessing the anonymous hash and assigning the result to $self?

In fact, in your example, it appears that $self could be done away with entirely:

sub new {
    my ($class, $foo) = @_;
    bless { foo => $foo } , $class;
}
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I understand that if new gets more involved and does more stuff with the object being created, that it would be a good thing to have a variable to work with. But it seems that the variable could be created and blessed first, then stocked with goods, and then returned, and I don't see any harm in it, though it isn't the way things are usually done.

sub new {
  my ($class, @args) = @_;
  my $self = bless {}, $class;
  # Do stuff with @args
  # ...
  # then return:
  $self;
}
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Where's the line between convention and Cargo Cult? This hints at being a meditation, except I don't really have the answers.