This year for North America and Europe there 2 Finals, in Sept.-Oct
In response to the backlash, Wizards entered into an agreement that they would never reprint certain cards again
Once you have enough spare copies of a card past 2 copies, you can exchange unnecessary copies plus some Shinedust for a Flair, which is a cosmetic option that can be applied to a card to make it stand out and look fancy
Emet-Selch just makes it that little bit better
In the past with just Kuldotha Rebirth it usually wasnt worthwhile since your odds of drawing a Kuldotha Rebirth wasnt especially high and cards like Ornithopter and Memnite are pretty bad if they aren't turning into three 1/1 Goblin tokens, but now the odds are in favor of having one in hand every game
If you can cast a spell with delve from your graveyard using flashback like the ability from Snapcaster Mage, you can apply all the rules from the mechanic