TYPO3 Core

While Symfony documents, that those polyfills could be replaced https://github.com/symfony/polyfill/#design
it does not mean that libraries should do so. In fact, even when documented by Symfony, adding a replace to a package, that in fact does not replace the functionality works, but is semantically still wrong.

This "hack" is quite acceptable for a concrete project, but should not be applied for libraries.

It is enough to declare PHP version constraints and leave it to concrete projects to add these replaces (or not).

As such: It would be fine to keep them for typo3/cms, but they should be removed from typo3/cms-core