although many do not like using map in a void context others find it more intuitive to operate on the entire array than looping through it's elements

It's not that I "do not like" map in void context, I just think it's redundant with a plain for loop. Now, grabbing the return values from map is not redundant with for, so I use it in those cases. As for your specific example, I would write that map line as:

    $sum{$_}++ for @array;
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Which is shorter, contains less syntax, and puts the most important part of the code at the beginning of the line.