Emacs merged with Pharo, not because of Smalltalk but of the GUI part, or being able to have a modern GUI inside Emacs native (no EAF) producing widgets in Emacs Lisp normally, so being able to have live widgets (custom included) in org-mode buffers.
And yes that's a "developer tool" because with both Emacs and Pharo (witch means classic user-programmable desktop environments, because that's what they really are) using a desktop is actually programming it as a normal daily activity where some just automate boring stuff, some others do a bit more complex automation in various shade of grey toward "system level" programmers, all with the same environment and work model instead of IBM-like (originally that's was) compartmentalization/separation of anything to make more profit and makes people feel powerless just impeding them to easily mold their own environments, at any level, programmers included.
And yes that's a "developer tool" because with both Emacs and Pharo (witch means classic user-programmable desktop environments, because that's what they really are) using a desktop is actually programming it as a normal daily activity where some just automate boring stuff, some others do a bit more complex automation in various shade of grey toward "system level" programmers, all with the same environment and work model instead of IBM-like (originally that's was) compartmentalization/separation of anything to make more profit and makes people feel powerless just impeding them to easily mold their own environments, at any level, programmers included.