Note that the filehandle is "local" and not "my".

Localizing a typeglob (let us be accurate here: what we call a "filehandle" is a typeglob from which Perl automagically extracts the IO slot) temporarily makes a different referent available by the same name. This is handy for avoiding conflicts elsewhere.

The alternative to your construct, using a lexical to contain a glob reference is also automagically understood by Perl and is, of course, lexically scoped.

At the risk of severe understatement, local is designed to allow scoped modifications of global names. It produces no special magic for filehandles (with the appropriate understanding that there is severe magic in perlio that doesn't apply here).

In other words, you can do it this way, but I can't see where it does you any good, since the standard approach does the same thing more idiomatically.