and because Perl's interpreter could potentially get this wrong, so could any human trying to understand the code.

I think it is less about people understanding the intent of the author, and more about having newer Perl users get frustrated when a syntax that worked in one part of the code doesn't work in a different part of the code. Perl has several of these problems, and we can eliminate one of them by giving up on the indirect method syntax.

An example of another ambiguity is when you want to generate multiple elements per iteration of "map".

%set= map { $_ => foo($_) } @list;
%set= map +( $_ => foo($_) ), @list;
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The first syntax is more idiomatic and looks better, but sometimes (depending on the code in the block and maybe also what comes after it) perl will decide that the block was a hashref notation and give you a nonsense error message. I've started always using the second notation just because it never parses incorrectly. This is *not* a universal recommendation, just a personal preference.