(This extension is archived so Ren-C can focus on other issues.)
The purpose of a GOB! was to be a more efficient data structure for manipulating a DOM-like heirarchy of items than trying to maintain a linked structure of Rebol values--e.g. with a parent and owner link done by object reference, and with lists of children having to be maintained as BLOCK!s. They have a fixed set of fields (including those related to coordinates, styles, and effects) but one of those fields provides for storing arbitrary data.
In order to export the data type, it was switched to a compromise of using arrays for the list of children, while using compact structures for coordinates and flags. Tradeoffs were made to keep GOB!s on the same order of magnitude as R3-Alpha, but able to build on more generally vetted code paths in the system.
For a long time, Ren-C kept the type around, while moving its implementation out of the core...to serve as an example of how one might define a new datatype in an extension:
https://forum.rebol.info/t/user-defined-datatype-discussion/1203
Proposals for a more generic NODE! type have been put forth, which would make more sense than having so many flags hardcoded for GUI purposes:
https://forum.rebol.info/t/multiply-linked-lists/1441 https://github.com/red/red/wiki/%5BPROP%5D-Node!-datatype