For many playtest cards, you'll need to make a generous assumption that basic game rules would be updated to allow them to work
There's also a reasonable number of "cast from your graveyard" mechanics at this point, including flashback, jump-start, and aftermath, so there are plenty of options available, although there aren't too many Commander staples that use a "cast from your graveyard" mechanic, so your power level might end up fairly low
Each trigger creates five artifacts in a 4-player game, which is conveniently enough to activate Time Sieve, and the rest is history
Moreover, you can only include cards in your Commanders color identity or artifacts
While Paradigm Shift is by no means the primary way most decks using Jace and/or the Oracle empty their library, it is a way to do it and thus it has seen play in Legacy and Vintage, where the Oracle especially is a very common win condition
Outside of a few very specific cards (which will be mentioned first) that require deck sizes above the minimum, all the other reasons you might want to are more fitting to casual magic: Battle of Wits - A win condition that specifically requires you to have more than 3 times the minimum deck size left in your deck to win means starting with about 4 times that minimum, if not more
