Exception "Impossible to invoke a method ("...") on an array" when passing a function to an included template

Consider the following Twig templates:

index.html.twig

{{ obj.foo() }}
{% include "partial.twig" with {
    obj2: {
        foo: obj.foo
    }
} %}

partial.twig

{{ obj2.foo() }}

And the following PHP script:

index.php

<?php

require_once 'vendor/autoload.php';

$loader = new \Twig\Loader\FilesystemLoader('.');
$twig = new \Twig\Environment($loader, [
    'strict_variables' => true
]);

class Foo {
    function foo() {
        return 'foo';
    }
}

echo $twig->render('index.html.twig', ['obj' => new Foo()]);

Running this script throws the exception "Impossible to invoke a method ("foo") on an array.".

It makes impossible to pass functions to included templates because Twig accepts function calls from class instances but not from its internal array representation.

We can narrow the issue to this:

echo $twig->render('index.html.twig', ['obj' => ['foo' => function() {
    return 'foo';
}]]);

I'm sure this is deliberate from Twig contributors. But, what is the rational against allowing calling functions that are part of the items contained into an array?

Start by reproducing the behavior with index.html.twig, partial.twig, and index.php from the report. Trace Twig's method-invocation handling for array values and callable functions, then determine the intended behavior and verify it with a focused regression test before resolving the issue.