More to the point, not only is "well, absence of proof is not proof of absence" flung around as a convenient dodge of the hard questions surrounding the Book of Mormon, let us ask this: What exactly WOULD constitute proof of absence (of evidence supporting the Book of Mormon)? Tell us EXACTLY what would be necessary to show that the Book of Mormon stories do not accurately portray ancient New World history and events.
I suspect there is no answer, I suspect that no amount of evidence would persuade the faithful, I suspect that no lack of pro-Book of Mormon evidence will get past faith presuppositions. Because some are already convinced that, "Joseph Smith was a prophet of God, and the Book of Mormon is historically authentic divine revelation." That is their premise to ALL discussions about the Book of Mormon. Ergo, ANY argument, ANY "evidence," ANY conjecture, ANY speculation--no matter how weak, poor, sloppy, half-baked, or self-contradictory--is acceptable if it somehow defends or leads to that premise. And NO argument, NO evidence--no matter how reasonable, careful, rigorous, overwhelming, irrefutable, or coherent--can possible prevail against the walls of Moroni 10:3-5 which surround that premise.
It is only when people are willing to question (not necessarily reject!) their faith presupposition, only when they are willing to look beyond or beneath the surface claims of the Book of Mormon and about Joseph Smith, that a truly substantive discussion can take place. Yes, I know, that is only a fair thing to say if the vindication of the Book of Mormon and of Joseph Smit is possible from such a discussion. Granted. But if a critique of the same is NOT possible from the very start because Moroni 10:3-5 is an a priori unquestionable premise, then the faithful waste our time with their apologetic arguments.
Why? Because they speak with their fingers in their ears. There is an absence of evidence for a great many things which no rational human beings believe in. If I theorize that space aliens occupied the earth 1,000,000 years ago and there is NO evidence for that theory, is it reasonable for me to complain, "Hey, absence of proof is not proof of absence"? Or would you dismiss me as irrational? See, in a different context that cliche no longer sounds so good, does it? [an error occurred while processing this directive]