Genuine question: Why does anyone run Convention of Elements?

I never ran it because it just logically seems like a really bad choice. The only damage type I care about is fire, so CoE only buffs my damage 1/7th of the time. That's only a 14.2486% uptime. With a damage bonus of 200% with a 14.2486% uptime, that's only an average damage increase of 28.4972% and CoE has no other benefits to speak of.

Seems to me like there are several better options unless you're actually dealing multiple types of elemental damage giving CoE a greater uptime.

Personally, I ran Obsidian Ring of the Zodiac instead. The damage and damage reduction increases I get from triggering more explosive blasts and more Black Holes is much, much more impactful than CoE.