True, Joseph Smith didn't explicitly say there were great multitudes of converts in Palmyra in 1820, but he didn't exclude Palmyra either, so it is ambiguous. (Joseph Smith's First Vision (Pt 2)-Dan Vogel, 5:03 mark)
In pt 1 of his First Vision video, explicit witness of the numeric distinction of the persons of the Father and Son in early LDS literature, including the Book of Mormon and Lecture on Faith no. 5, but because the term "person" was not used, it still can be consistent with Vogel's bogus claim early Mormon Christology was that of Modalism. But when it comes to his anti-Mormon agenda, well, double standards and more "Vogelian" special pleading.