The short answer is that

• you can bless any reference in Perl to get objects - not only hashes like in most other languages
• type-glob refs exist \*glob
• *$self is the proper way to deref a glob-ref

I personally find file-handles and type-globs a bit messy and it always takes me some time to re-understand all the quirks again.

I think that's mainly - like so often - because of the transit from bare-word handles FH to lexical $fh and the need to keep Perl4 code backwards compatible.

Once you want to work the internals of IO-objects you need that syntax.

update

https://perldoc.perl.org/perlmod#Symbol-Tables

https://perldoc.perl.org/perlobj#Method-Calls-on-Filehandles

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