but that seems to be easily remedied with anchors in the expression (and -- for ease of illustration -- using a defined array rather than @ARGV):

#!/usr/bin/perl
use 5.014;

my $count;
my @arr = qw/helper abc help def helpless helpful whelp help/;
$count = grep {/^help$/}@arr and print "This is a help message. ";    
+# Note1
say "\$count: $count";

# This is a help message. $count: 2
[download]

^Note1: can also be written $count = grep /^help$/, @arr ....