Can we avoid toString() in build methods?

When looking at this code, being part of LinksWidget.php in the buildListItems method:

      $items = [
        '#markup' => $link->toString(),
        '#wrapper_attributes' => [
          'class' => $classes,
        ],
        'children' => [$children_markup],
      ];

We are essentially rendering the Link already in the build method.

Feels like we are mixing up the build + the render phase? Asking if we can improve this :)