Cards like Squee, Dubious Monarch in Standard can provide the celebration trigger each turn, and Voldaren Epicure and Bloodtithe Harvester can do it too
As a side note, the fact that your opponent will have to spend mana on a combat trick instead of anything else (like casting another creature) should make you more inclined to block
Here is Exhibit A, I could find an Exhibit B if you needed it, but I kind of feel like anyone who needed that would have acquitted OJ
They work against mill in a similar fashion: Shuffling your library back into your deck against a mill deck is equivalent to resetting your life total to 20, 40, or whatever against a more standard Magic deck attacking your life total
Namely, that Commander was ruining other formats and warping competitive play
Player two sees a single card that they can bottom or draw