I think that the biggest win with this feature, is not that PHP will do more runtime type checks, but that the syntax is valid.

The past years we've seen several static analysers become more and more popular in the PHP community. Tools like phpstan (https://github.com/phpstan/phpstan) and psalm by Vimeo (https://github.com/vimeo/psalm).

Allowing this syntax is a great way to write cleaner code that can be statically analysed, which is far more superior than the runtime type checker.