Yes you are right, the collodion does make for a better image but this is more of a simpler substitute that makes tintyping more easy to do with a minimum of materials and equipment and less fuss. The big advantage is not having to drag all that darkroom stuff out into the field and put it all back later that evening. Compaired to wetplate this is a toy.
I have no intention of abandoning the wetplate but some times I wonder.
The dry collodion plate is a captol variation for field work(negatives only).