Im glad that it exists in Arena the way it is
There's no real number, but control decks generally run fewer creatures than other archetypes
Storm decks are tough to beat with countermagic alone as are most non-linear combo decks of that ilk
We were so happy with connive in Magic: The Gathering | Marvel Super Heroes that we retroactively added it to Magic: The Gathering | Marvel's Spider-Man , which was still in set design at the time, to provide more of a mechanical throughline between our Marvel sets and enable cards with mayhem
In contrast, Magic: The Gathering is far more flexible about how many players are involved in a game, and the game's card design reflects that
If the discard was something more universal like lands or blue cards instead of artifacts, or always just one card, while retaining its instant cost it would probably get more play than Fact or Fiction, mostly for occupying a slot on the curve in less demand