I can only speculate what you are meaning, cause you neither cite sources nor do you show code.

  DB<102> open $x, ">", "/tmp/tst";

  DB<103> $x
 => \*main::$x

  DB<104> STDIN
 => "STDIN"

  DB<105> \*STDIN
 => \*main::STDIN
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As you can see do lexical file handles actually hold references to globs, i.e. '\*'.

I never heard that this is generally "considered good syntax", but if you need to store "normal" file handles in variables you'll need this construction.

 my $x = \*STDIN

see also perldata#Typeglobs-and-Filehandles