They were a good indicator for notifications that are missed when you were away from phone.
Higher end Smartphones have anyway always on displays. And the led needs screenspace - which should be maximized. That’s why the notch on phones etc. was introduced.
The led can just be put in the speaker grill though, I think my old HTC did this.
Modern smartphones hardly have any edges and therefore hardly any space for an LED at the notch. In addition, the pixels of AMOLED displays can be controlled individually, which allows displaying notifications well and consumes little power at the same time.
On Samsung phones your whole screen flashes in a custom color and and animation, and after that you have your always on display. So they are no longer needed with OLED screens that can display it themselves
That seems to me a waaay too inefficient indicator of “you have unread notifications”
The whole front of modern phone is a display, there’s simply no space for a notification LED.