here's a great video going over all the pros and cons
www.youtube.com/watch?v=7BkX...

the argument is that they were originally designed to be playable in monocolor decks so they should also be playable in monocolor commander decks.

which is an odd argument, given that EDH as a format has always deviated from the original design intent. color identity is an EDH-exclusice concept.

e.g. should you be able to play Kenrith in a mono white deck? maybe, but then how do you justify his 5-color identity within the same rule?
should you be able to play Archangel Avacyn in a mono white deck? maybe, but then how do you justify her color identity also being boros at the same time?

the problem is that the concept of color identity works both ways: Rhys the Redeemed has a white-green color identity in the command zone so he should also have it in the 99.
it's confusing if you make it inconsistent and it gets even worse if you extend it to other not-quite-multicolor cards.

maybe we should go back to "you can only produce mana in your commander's color identity" from pre-2017, then we wouldn't really need to restrict the deck construction anymore

yeah that's true. color identity is a pretty consistent rule and it would become worse if it had specific exceptions.
imo the only alternative is to abolish the idea of color identity entirely.

just a tiny bit too expensive to keep

that sounds like a black card, not a red card (11 out of 11 archfiends in Magic are black)

oh shit i might have to watch this one

nice