You can do other things at the same time until your artifact is answered with more activations, and in the context of counter decks it is a repeatable way to add counters (which will undoubtedly add counters... and more counters).
Which is like..fine. I don't think WOTC went "Lets make a card that exists only to set up rube goldberg machines just for commander players"
Yeah but not much like Relic of Progenitus
Which isn't really playable anymore (largely because the first ability is opponents choice)
Yeah, but not as graveyard hate as a combo card.
If Yawg were still a Tier one deck it would be for both, there are quite a few reanimator decks in the top tier at the moment. (and Eating Grief was relevant during Scam's dominance.)
It's only worth putting in your deck or sideboard IF you can abuse with cards you have brought or if it's a metagame call to fuck with people who are using it as a combo.
That is only because there are largely better options, which means it is kind of working as intended, if you can use the marginal value you use it. If not you you use ghost vacuum.
It sees no play for that, when it was printed it didn't replace Hearse in standard or existing graveyard hate in modern (except in the one creature based combo deck using activated abilities) and when vacuum was printed it replaced hearse (because it's 1 mana and it's late game fallback mode is better)
That is because Hearse is a win condition without having to have a combo set up, as is ghost vacuum. It's good in..decks that specifically want counters and activated abilities which is a pretty thin line.
Wizards of the Coast will literally make a set called Modern Horizons and put EDH decks into it and EDH players will still tell you they don't design for EDH.
And people will blame EDH on every bad design despite the cards not being particularly great in EDH. Soul Cauldron doesn't even played that much in EDH.
Do you know how many of the major +1/+1 counter commanders even have activated abilities? One in the Top 10, 3 in the top 30 and Soul Cauldron isn't highly represented in any of them despite the fact it probably should because responsible players have graveyard hate. Hell looking at a Commander probably made for Soul Cauldron. Ramos, Dragon Engine its not even on his EDH rec page as represented at all.
Hey you know what else Modern Horizon decks aren't called? Draft Horizons..yet they probably designed more cards for Drafting than they actually did Modern, yet nobody cries about random Draft chaff ruining formats which I guarantee has happened more than with EDH.
Soul Cauldron doesn't exist because of EDH, it exists because "Graveyard hate with upside" has been a thing they have been doing for a few years because Graveyard hate has kind of fallen behind in power and after 3 years it managed to do something relevant...in what is in my opinion one of the single worst "Overpowered" Decks in years because outside of specifically how Cauldron and Vivi interact with +1/+1 counters that deck is full of god awful cards.
I was never a fan of the cantrip Izzet decks like Pheonix but I can play the Pheonix deck and not wanna kill myself. Every time I cast Winternight Stories I just wanna shoot myself cause I could be casting Stock Up for the same mana also at sorcery speed and I am not a particular fan of stock up (Gimme my card draw at instant speed thank you very much)