I mean on a historical/archeology level?
Seems to me....with the Billions of $$$ that LDS, Inc has...they'd be throwing money everywhere...to find evidence of these cities...To PROVE once and for all...to the world that the BOM is true.
Why aren't they?
Why are they not spending the money to find what remains these places? ... Because even if they do not nor have ever existed physically, the cult mind insists on believing the places exist/existed somehow because to doubt they ever existed would be the same as denying the false prophet, Joseph Smith. ... But they will not admit that to you until they get out of the cult.
Simple: they don't need to.
They have enough folks deceived now to continue paying their tithes to keep the Leadership in the lifestyle to which they are now accustomed.