where parens often indicate to the reader that he is looking at a list.

You say foreach (), I say while () and if ().

You say my ($x,$y,$z) = @_;, I say ($x+$y+$z)*$n.

The parens in foreach(),

The parens of foreach not even part of the expression, and the list is still created when you omit them.

say foreach "a", "b";
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Or to put it differently, they indicate it's not an array and not a hash (and not a scalar).

Really?

$s = ($x);
%h = ($x);
%h = ([]);
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Your model has too many holes to count :(

Simple model: A list is created whenever something is evaluated in list context.