@ARGV is something perl make at disposal for you: if you know what are you doing you can modify at your will: inserting or shifting from it.

Rare items Perl gives you are bad to modify: some of the puncuation variables are a good example to be bad to modify. What the need to modify $. current line number for example? Or what you gain setting $^O the operating system label?

@ARGV and many other varibles you have at disposal are useful to modify. Getopt::Long make a lot of work on @ARGV even if principally shifting it.

But consider you want to write a simple program, possibly a oneliner, that glob files and unfortunately you are working in a user unfriendly OS that does not glob files on command line. You can use glob expanding @ARGV in a BEGIN block:

perl -lne "BEGIN { @ARGV =  map glob, @ARGV; print qq(considering ).scalar @ARGV.qq( files\n);} ....

Or you want to have the first file processed to be the comparing stone and the following ones searched just for lines present in the first one:

perl -lne "%ln;BEGIN{open $f,shift;map{chomp;$ln{$_}++}<$f>}print qq($
+ARGV line\t$.\t[$_]) if exists $ln{$_};close ARGV if eof" 
           dog.txt cat.txt other.txt
[download]

Or, if you have enough hubrys, want to evaluate some line number range popped from @ARGV while printing just some line of a file:

perl -E    "say+(0,<>)[eval pop]"                          linenumber.txt 1,3..5

So, imho, modify @ARGV if you need to!

L*