Sorry...but the way you state this is completely inaccurate.
First of all, there are conditions even for this coerced arrangement:
One such "condition" is if the dead man did not leave a son to carry on his name.
So...that automatically left out ALL moms who already had sons.
A second condition was for those brothers to have ALREADY been living together (v. 5).
That condition then did not REQUIRE that even a sonless wife move in with her brother-in-law.
Then, on top of all of that, my reading of Deut. 25 -- and you'll have to give me additional sources for me to consider something different here -- doesn't assume that the remaining brother-in-law is already married.
It may have been assumed in that culture that this applied to an unmarried brother-in-law.
Finally, we also know that if the widow's sister was married to this "live-in" brother-in-law, then Leviticus 18:18 specifically forbid any such "arrangement": 18 Do not take your wifes sister as a rival wife and have sexual relations with her while your wife is living."
I also note that while you cite Deut. 25, you didn't cite Deut. 17:17: 17 He must not take many wives...
THE BOOK OF JACOB
THE BROTHER OF NEPHICHAPTER 224 Behold, David and Solomon truly had many wives and concubines, which thing was abominable before me, saith the Lord.
25 Wherefore, thus saith the Lord, I have led this people forth out of the land of Jerusalem, by the power of mine arm, that I might raise up unto me a righteous branch from the fruit of the loins of Joseph.
26 Wherefore, I the Lord God will not suffer that this people shall do like unto them of old.
27 Wherefore, my brethren, hear me, and hearken to the word of the Lord: For there shall not any man among you have save it be one wife; and concubines he shall have none;
28 For I, the Lord God, delight in the chastity of women. And whoredoms are an abomination before me; thus saith the Lord of Hosts.
29 Wherefore, this people shall keep my commandments, saith the Lord of Hosts, or cursed be the land for their sakes.
30 For if I will, saith the Lord of Hosts, raise up seed unto me, I will command my people; otherwise they shall hearken unto these things.
31 For behold, I, the Lord, have seen the sorrow, and heard the mourning of the daughters of my people in the land of Jerusalem, yea, and in all the lands of my people, because of the wickedness and abominations of their husbands.
32 And I will not suffer, saith the Lord of Hosts, that the cries of the fair daughters of this people, which I have led out of the land of Jerusalem, shall come up unto me against the men of my people, saith the Lord of Hosts.
Or even HERE:
1 Timothy 3:2-3
2. Now the overseer must be above reproach, the husband of but one wife, temperate, self-controlled, respectable, hospitable, able to teach,
3. not given to drunkenness, not violent but gentle, not quarrelsome, not a lover of money.1 Timothy 3:12
A deacon must be the husband of but one wife and must manage his children and his household well.Titus 1:6
An elder must be blameless, the husband of but one wife, a man whose children believe and are not open to the charge of being wild and disobedient.
THE
DOCTRINE AND COVENANTS
OF THE CHURCH OF JESUS CHRIST OF LATTER-DAY SAINTSSECTION 1325157, Emma Smith is counseled (commanded) to be faithful and true; 5866, Laws governing the plurality of wives are set forth.51 Verily, I say unto you: A commandment I give unto mine handmaid, Emma Smith, your wife, whom I have given unto you, that she stay herself and partake not of that which I commanded you to offer unto her; for I did it, saith the Lord, to aprove you all, as I did Abraham, and that I might require an offering at your hand, by covenant and sacrifice.52 And let mine handmaid, Emma Smith, areceive all those that have been given unto my servant Joseph, and who are virtuous and pure before me; and those who are not pure, and have said they were pure, shall be destroyed, saith the Lord God.53 For I am the Lord thy God, and ye shall obey my voice; and I give unto my servant Joseph that he shall be made ruler over many things; for he hath been afaithful over a few things, and from henceforth I will strengthen him.55 But if she will not abide this commandment, then shall my servant Joseph do all things for her, even as he hath said; and I will bless him and multiply him and give unto him an ahundredfold in this world, of fathers and mothers, brothers and sisters, houses and lands, wives and children, and crowns of beternal lives in the eternal worlds.
You bring up only tangentially associated points. Yes there are several restrictions. must be male must be brother must be....
That does not change the original requirement of the law. Further, it misses the point of my post. The original comment that I was responding to was the assertion that God only tolerated polygamy and never commanded it. Deu 25: 5-6 flatly rebuts that assertion.
Further, you are reaching when you attempt to assert that the culture may have assumed that the marriage would not have been allowed. This is because we KNOW that Jews practiced polygamy. While it was not widespread due to the need to support those “extra” wives, the practice was never banded under OT law. Further, there are OT laws about not only the treatment of wives, but concubines as well. See Exod 21:7-10
As for Deu 17:17 go back and read 17:16 as well. It says he must not multiply horses and then it says he must not multiply wives. Do you really think it is a reasonable assertion to limit the king to ONE horse? Kind David was a man after God’s own hart (Acts 13:22), yet we know he had two wives and possibly others before he was anointed king.