There is Unicode support
There is a proposal for generics https://wiki.php.net/rfc/generics
For me personally its not a deal-breaker, there are workarounds if needed.
but for your question, why not?
It's so frustrating to see people just suggesting the "Mainstream" without considering if OP even asked.
Edit : Unicode support is not native. So concede this one, but again not a deal breaker as a language IMO.