With the release of top notch delve cards from Tarkir, the delirium mechanic things, flashback stuff, recursive dorks, and even just an increase in good graveyard recursion effects there is a significant increase to the value of self mill
They fit standard-sized cards perfectly and are praised for their clarity and shuffle feel
It fits naturally in legend-heavy builds and sees play in Murktide, control, and combo decks that value instant-speed answers without sacrificing land slots
The deck then adds support through powerful ramp effects, removal spells, anthem effects, etc
Copy all are some strong words to use, and thanks to Modern Horizons 3 you have plenty of inexpensive, non-rare eldrazi that slot in nicely such as Writhing Chrysalis, Glaring Fleshraker, and It That Heralds the End
Even more, I do happened to have a healthy number of planeswalkers in the deck, so cheating into play isn't too hard