Actually, you can not find shrines like those on Mauna Kea "everywhere on the island where there are stackable rocks."   The uprights that I mentioned in point 3 of my last comment are distinctive and unusual.  In addition to Mauna Kea, shrines with similar uprights are found on Nihoa and Mokumanamana in the northwest Hawaiian Islands, and at one structure at `Ilio Point on Moloka`i.  They are not found other places in the Hawaiian Islands.

Similar shrines are also found in the Tuamotu and Society Islands, which is one reason archaeologists are particularly interested in them, and perhaps a factor in why the protectors are making the claim the mountain is sacred.

Archaeologists are confident these shrines are ancient, but recognize that their ideas are fallible.  If you have information that the many dozens of shrines with upright stones on Mauna Kea are recently made, please share it.