Mormonism started as a typical cult based on sex, power, and wealth for its promiscuous sex-hungry leader so it isn’t surprising that its sex-based core will always be a problem for it and with a fundamental part of the cult being the availability of females, age lines and incest lines will always be especially hard to maintain in that cult.
Now that marriage has become basically whatever consenting adults want it to be, in time we will probably see new prophet revelations returning open polygamy to the Mormon religion.
when your “throuple” is threatened by a “quadrouple” and “quintouple” THEN you can worry. oh what’s the use. never mind.