In the early stages of JavaScript it was not possible to remove an element directly. Was necessary:

element.parentNode.removeChild(element);

Later a direct function was added:

element.remove();

All browsers have added support for this function, except Internet Explorer. Now that Internet Explorer is no longer supported and the minimum JavaScript version is ES6, I believe MediaWiki should be updated. It makes the code smaller and more direct.

In a direct search of the MediaWiki source code:
https://codesearch.wmcloud.org/search/?q=removeChild

We see that several scripts use the older, longer method, as an example:
https://gerrit.wikimedia.org/g/mediawiki/core/+/dfd748033e5ab7272ef52f5b5425c28a35e0cbec/resources/lib/vue/vue.global.js#9635

Which is:

remove: (child) => {
  const parent = child.parentNode;
  if (parent) {
    parent.removeChild(child);
  }
}

But it can be simplified to:

remove: (child) => {
  child.remove();
}