foreach loop, the last value of the array being looped over remains after the end of the
foreach loop. That is why one should actually always unset that value after the
foreach loop is done.
wp_list_pluck() is also just a basic
foreach loop if
$index_key is not passed. Also, as with any
foreach loop, the last value of the array remains after the end of the
foreach loop, and I think this is what that line refers to in the codex.
However, that assumption is wrong. Functions are self contained pieces of code, and except for globals, these pieces of code inside a function are only avaiable to the function itself.
wp_list_pluck() does not globalize any of its intenal values (variables), so even if the last value of the array is still available after the
foreach loop inside the function, and does not get unset, it is not available to any piece of code outside the function, so you cannot have the pass-by-reference issue as described in that line in the codex.
wp_list_pluck() is as valid to use as any simple
foreach loop. The choice is up to you. I personally prefer
wp_list_pluck() as it saves on code, and you do not need to remember to unset variables which can later lead to debugging nightmare.
Just a final note,
wp_list_pluck() can also replace
array_column as it works the same if
$index_key is passed to the function