formBuilder()->getForm() outputs everything except the  tag in a view?
Looks like views reformats rendering as a form if there are any form elements in a row. See \Drupal\views\Plugin\views\display\DisplayPluginBase::elementPreRender:
    // If form fields were found in the view, reformat the view output as a form.
    if ($view-&gt;hasFormElements()) {
      .....
    }

I guess you should see one &lt;form&gt; tag arround the entire view.
In this case a possible solution would be to create a custom views display plugin Forms, that overrides the elementPreRender method and ignores the form elements check.