You can’t learn the whole stack. Nobody can. Maybe it was possible in 1990, the day after the web was invented, but I’m not even sure about that. The stack grows and shifts and evolves every day.
Very much agree with everything here: You Will Never Be A Full Stack Developer and is something I’ve touched on before. In my client work, I’m increasing seeing a need for specialists working together and varying degrees of organizational success in accomplishing that. It can be tough to orchestrate developers who specialize in different parts of the stack, but it’s something that is increasingly necessary. This should be on tech leadership’s mind, but in my experience it tends to be a blind spot.