I agree, Smith built upon the views of Campbell, Smith’s theology was evolving in the early years and that can be seen clearly as can Campbell’s influence. There are some good studies on the relationship between the two.
Dan Vogel, D. Michael Quinn and the recent Rigdon Bio also have quite a bit of info on the two groups and their connections.
“I agree, Smith built upon the views of Campbell, Smith’s”
would more state that rigdon provided a base then smith et.al distorted (beyond reason) the most basic tenets of the restoration movement more so then built upon them.