First of all, some form of graphic chips/circuits are around as long as we have CPU’s - read HERE and HERE
Basically every PC, Laptop, Console, Mobile (Windows, Mac, Android, Linux, Unix, etc…) that connects to a monitor/display has a graphic processor/chip/circuit in some form or another, otherwise you can’t display any image to the Monitor directly.
Graphic chips can be either dedicated or integrated, in both cases their job is the same - displaying images to your display.
The main differences are performance and/or requirements.
On the other hand the main job of a CPU is different to the work of a GPU, therefor the architecture and development is different from each other.
Some CPU’s even have a graphics chip integrated into them, its usually called a discrete GPU these days.
A GPU is very bad at running an OS, Excel, browsing the Internet - but very good at calculating graphics.
GPU needs to render Graphics
A CPU is good at running an OS, Excel, browsing the Internet and can calculate basic graphics.
CPU’s need to run your PC, Phone, Car, TV, Radio, etc…
Due to this, the development is different.
Here is a very simplified version.
step 1: getting faster speed - hotter - using more power - adding new features
step 2: running colder - using less power - not or slightly faster - adding new features
step 3: go to step 1
step 1: faster, new features, getting hotter/colder, using more/less/same power
step 2: modify, enhance, tweak
step 2: go to step 1