> It will happily accept string in a array of dates, for example

While completely true, you are using static analyzer anyway which won’t let you do this.

The generics support will likely come in the near future, there has been momentum in it again: https://thephp.foundation/blog/2025/08/05/compile-generics/

I'm working in PHP for about 15 years by now, and for about 10 of them I was promised generics. In favor of your health, don't hold your breath.