Anything specific to it that you want to inquire?
I think this limitations is roughly saying that offset will need time/disk-access linear to size of offset used. Since, it will need to skip offset number of keys after finding the pivot key.
If you can describe the usecase you have in mind to use large offsets, then someone here should be able to suggest an optimal approach.
Just to make sure - this offset limitation is unrelated to “searching” the BEGIN and END keys in getrange operations (for operations you described above).