This is perfectly justifiable, as Iymrith looks to be a future staple in many control decks, as well as, other archetypes
Sacrifice after III.) I Scry 4, then you may reveal the top card of your library
Lurrus of the Dream-Den: Banned in Legacy and Vintage Lutri, the Spellchaser: Banned in Commander and Brawl Zirda, the Dawnwaker: Banned in Legacy Additionally, Yorion, Sky Nomad cannot be your companion in any format with a fixed deck size, including Commander and Brawl
Still, for decks that care about fast, reliable mana across multiple colors, it's proving to be well worth the cost
Historic cards can be powerful, but a more legendary or historic build is just significantly weaker than focusing on artifacts
The question is whether it's better to use Solemnity in this role over Anafenza, Kin-Tree Spirit or Melira, Sylvok Outcast, and while the answer is generally no (mostly because Anafenza and Melira can be found with Chord of Calling and Collected Company while Solemnity cannot), it's worth keeping in mind because, as an enchantment, Solemnity is much harder to kill than a random Grizzly Bear