It says the one on whom is conferred “keys of this priesthood” (or the authority to confer priesthood on others), so the high priest, or prophet, such as Joseph Smith, or his successors. Even to this day, Smith’s successors are referred more often to as “prophets” than as “high priests”:
“God has called prophets to lead His Church in our day, just as He did anciently. The current prophet and President of The Church of Jesus Christ of Latter-day Saints is Thomas S. Monson.”
http://www.mormon.org/faq/present-day-prophet
I don’t see how there is any room to argue here that this section only applies to the high priest. Polygamy was in general practice in Smith’s day, by all Mormons. If that wasn’t his intention, he would have surely said “no, this only applies to me!”, but he did not do that.
Polygamy was in general practice in Smith’s day, by all Mormons.
The power was conferred to Joseph, but there were different versions of priests and as time went by there were more included.
The book of Mormon forbids polygamy so it is doubtful that all of the different priests would be included, but I believe it was meant for Emma and very doubtful if it had anything serious to do with any thing else.
I like my Bible much better than I do the book of Mormon because it does not forbid polygamy, not that I am up to it and never have been but I believe it may work for some.