One can make an obscure scripture mean whatever one wants it to. Who's going to know that it probably means something different? In a sense, the more obscure the better, eh?
pretty much nothing at all other than a few brain farts by some old guy of questionable intelligence, who should probably have been committed to a mental institution for going around calling himself a prophet.
I think baptism for the dead started with the Smith family grief that Alvin never got to participate in their religious revolution. IMHO. Has nothing to do with any obscure Biblical verse. That is an ad hoc.
There was a ward Temple Baptism trip for the youth. Uncle decided I should participate -- that it would be good for me. He forgot that I had only been baptized Catholic, never LDS - only blessed there. Anyway, these people from a stake 800 miles from my home arranged the interviews. One Uncle gave Bishop's interview. Other uncle gave stake presidency interview. They knew I wasn't actually worthy but were clueless as to just how unworthy I really was. so I went on the trip and was necro-dunked about 40 times despite never having been formally dunked on my own behalf. I was a lightweight and had no physical development in the breast department, which made me a great candidate.
When the mistake was discovered a few days later, the ewlatives of course blamed me. I didn't know I had to have been baptized to participate in the ordinance. The workers had to go back and discover which people I had been baptized for and redunk someone else for them. I'm not sure how careful their records were as to whom was being dunked for whom, so they probably made wild guesses. My relatives looked at it as one more way I tried to thwart the progress of the Fullness of Times. I didn't even know I was doing such a thing. Truth of the mtter is I probably would have done it anyway even if I had known.