The lack of these functions in the "single trivial value" and "sliced GVArray" implementations caused some code to call fack to the base class functions. Those are much slower since they involve a virtual function call per element. For example, this changed the runtime of creating a new boolean attribute set to "true" on one million faces from 3.4 ms to 0.35 ms. Pull Request: https://projects.blender.org/blender/blender/pulls/118161