Modern GUIs have no extensibility, they are designed from the widget library to the entire software as commercial product, FOSS included because the idea of "modern" GUIs is commercial at design stage.
Emacs, like LispM, Xerox ancient worsktation etc instead was born in a world where software is free, only hardware is commercial. So they are designed from start to be flexible, user-centric, non product-centric.
It's worth remembering an ancient joke of MIT AI lab: An engineer ask few secretaries if they know how to program; they respond no. It ask if they were sure; they respond "of course". As a matter fact they use Emacs and program the mode they need, only no one tell them that's programming, they simply learn how to bend a flexible environment to their needs. Another thing worth mentioned is the classic "In the beginning was the command line" paper, short and nice.
Unfortunately people born in commercial world that do not know IT history can't really imaging that world and it's power. They are incapable of think outside actual business model so they do not understand that other models and software exists...
Emacs, like LispM, Xerox ancient worsktation etc instead was born in a world where software is free, only hardware is commercial. So they are designed from start to be flexible, user-centric, non product-centric.
It's worth remembering an ancient joke of MIT AI lab: An engineer ask few secretaries if they know how to program; they respond no. It ask if they were sure; they respond "of course". As a matter fact they use Emacs and program the mode they need, only no one tell them that's programming, they simply learn how to bend a flexible environment to their needs. Another thing worth mentioned is the classic "In the beginning was the command line" paper, short and nice.
Unfortunately people born in commercial world that do not know IT history can't really imaging that world and it's power. They are incapable of think outside actual business model so they do not understand that other models and software exists...