Presets are not visible IN folders: so "retain the folder" does not really apply IMO.
Rather, each preset has within its structured syntax, a Group it is stated as belonging to.
This is a matter of intentional design by the supplier of the preset, and allows meaningful groupings and associations to be embedded inside the individual presets themselves. Without requiring any particular hierarchies of physical folders to exist.
Not as the source for importing presets, not as the result from doing so.
Each time LrC starts up it scans for whatever presets it can find irrespective of subfolders. All the Groups encountered within these presets' internal metadata, duly appear - presented as an organising structure, but one which is purely virtual.