I disagree as to the bogosity of this practice. There is nothing wrong with adding clarity to a statement that may otherwise be confusing or ambiguous. And there is nothing wrong with reducing the number of rules someone needs to know in order to correctly decipher a statement.

This is just such a case, because an argument given to print can start with either a filehandle or a variable. Depending on what follows, it can be very hard to tell which is intended without braces.

I do enjoy how Perl lets one push the boundaries of acceptable syntax, but that doesn't mean it's always a good idea to do so. That's just my opinion, of course.

There is nothing wrong with adding clarity to a statement that may otherwise be confusing or ambiguous. And there is nothing wrong with reducing the number of rules someone needs to know in order to correctly decipher a statement.

How does it add clarity or reduce the number or rules?

perldoc -f print starts with

print FILEHANDLE LIST
print FILEHANDLE
print LIST

print { EXPR } LIST is not on the list at all

Where is the ambiguity?

     print  $fh  map { "$_\n" } @list;
     print {$fh} map { "$_\n" } @list;
$fh->print(      map { "$_\n" } @list );
     print( $fh  map { "$_\n" } @list );
    print( {$fh} map { "$_\n" } @list );


     print  $fh  @list;
     print {$fh} @list;
$fh->print(      @list );
     print( $fh  @list );
    print( {$fh} @list );
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This is just such a case, because an argument given to print can start with either a filehandle or a variable. Depending on what follows, it can be very hard to tell which is intended without braces.

They're both called filehandles, both STDOUT and $fh, the first argument to print is always an optional filehandle followed by a LIST

STDOUT is a bareword filehandle and $fh is a lexical-scalar filehandle

And now try it with

my %handle = ( out => *STDOUT,
               err => *STDERR );
print {$handle{out}} "Test\n"; # Not possible without braces.
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لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ

I do understand the syntax of Perl filehandles. The ambiguity comes between printing to a filehandle and printing a variable to STDOUT. i.e.:

open my $f, '>out.txt' or die 'ouch!';
print $f 'foo';

...

my $f = 'bar';
print $f, 'foo';
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These two similar looking print statements do something very different. It is not a big deal in this case, but when you replace 'foo' with an expression it can be hard to tell whether $f is a filehandle or a variable. In fact, sometimes even the interpreter can't tell, as the documentation you linked to points out:

(NOTE: If FILEHANDLE is a variable and the next token is a term, it may be misinterpreted as an operator unless you interpose a + or put parentheses around the arguments.)

Here is a simple example that the compiler can't correctly handle without braces:

use warnings;
use strict;

open my $f, '>out.txt' or die 'ouch!';
$_=' eeee';
my $e='e';

#supposed to be a pattern match, but interpreted as division.
print $f / $e/ ? 'yes' : 'no';
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When's the last time you used duct tape on a duct? --Larry Wall