Polygamy was the norm for most of ancient/imperial China, Ottoman Empire, Mongols, Ancient Jews etc.
I wouldn't go so far as to say it was the norm for most people at most points in history, but considering the populations of the above civilisations it wasn't uncommon either.
FWIW, in ancient China people strictly only have one wife in most cases. The others are called concubines (I think). They have very different social/legal status.
Islam prohibits more than 4 wives and obliges the husband to treat every wife equally, so much so that most men who are even rich enough to marry more than one wife don’t due to of fears of not being able to treat them equally. (rich enough: women need not work in Islam. Their husband, relatives, and the state is obliged to provide for them in this order) That’s the best solution.
What do you mean "to deal with"? There's a lot of misconceptions about marriage, having to "manage" your spouse is one of them. You don't, they're their own person, they can take care of themselves, and if they're dependent on you it's not a healthy marriage.
A healthy marriage of two people treating each other as equals takes a lot of communication, and that almost certainly can't be scaled 10x, nor do the same principles apply when someone is only getting 10%.
In traditional polygamy, the man with 10 wives would be the head of household for 10 wives with competing interests, so it does start to sound very managerial.
I recall reading an interview of a higher-up in the Saudi government. He was asked why he doesn't have multiple wives. He replied that he doesn't have enough free time for that lifestyle. His grandfather was a tribesman: they raided other tribes about once a month to get what they needed. His father was a farmer/grazier: he worked about once a week. He, himself, is a government official and works most days.
I think Esther Perel has written the best stuff on modern relationships. Read her.