i don't expect anyone here to know who viscant is, but i think you understand what i'm getting at there. so i'd be interested to hear how you feel about this topic, how accurate you think i'm being with this, etc. hopefully i didn't screw up the urchin point too badly!
Why don't you expect that, who doesn't know their mahvel evo champs?
This is a comparison I've thought about myself, and I think IF Dominion were online only (i.e. no dead tree edition), or a video game, or if Donald X was willing to consider the online game a full-fledged spinoff, then I would expect updates to existing cards, in addition to expansions.
In fact I think the buff/nerf cycle would work better than it does in fighting games for two reasons, both of which you touched on. First, we're dealing with one long-lived game, rather than the relatively short cycles of say SF or MK, so there's time to let a card breathe in the wild before you change it, and even time enough for multiple long cycles with the same card.
Second, in Dominion if a "top tier" card shows up on a random board, both players have access to it, so you're not all that worried about plain power. It's more about whether a card limits the good decisions you can make which requires the card to both be powerful AND interact poorly with other cards.
So I think the call for card changes would be somewhat rare, and when it did arise you'd be able to take a more considered approach than fighting games, and also make subtler changes that are about card interaction, not just power.
Let's take Cultist as an example since it hasn't received much love in this thread. Usually, I don't like it much. A deck full of both junk and terminal draw has room for little else, so it interacts poorly with other kingdom cards. UNLESS there is good enough trashing to lose the junk. In those rare games where you can use Cultist as your draw card in an engine, I love how the stacking mechanic makes it unique among Smithy variants. So suppose we want Cultist to interact better with villages. There's a ton of ways we could change it but the simplest I've come up with is to add four words...
Currently: You may play another Cultist. Each other player gains a Ruins.
Changed: You may play another Cultist.
If you do not, each other player gains a Ruins.
It junks quite a bit less now, but can still draw a lot, and can hand out multiple Ruins in a turn if there are extra actions available to let you play them "un-chained." So it's still a really strong card, but I think that version would play a lot better with other cards.
And I think most cards that got touched at all would have changes that small and simple. Try fixing Evil Ryu that easily