Changing system partitions is a delicate matter. For Linux and Wind°ws host machines there are easy to use tools. For Android phones the danger of making the device unusable is very high.
A disadvantage of new firmware is often the ever-increasing software libraries, which carry a lot of ballast and unnecessarily inflate the image.
While it is true that creating new applications with these software libraries is faster than creating them in pure machine language
(I think here for example of machine-oriented programming with assembler). Instead of programming effectively, more powerful hardware is used to compensate for this shortcoming.
Yeah! This minimal eOS pie version /e/ OS ROM shows what is possible with simple means.