Why must the sideboard be exactly 0 or 8 cards in Riftbound, rather than allowing 0-8 cards?

Ruling: The sideboard must be exactly 0 or 8 cards to ensure exact registration numbers for events and to enable deck verification at events without deck lists.

Nuances:

• Since you must take out as many cards as you sideboard in, having a variable sideboard size would make it impossible to verify an opponent wasn't cheating at events without deck lists
• This differs from games like Magic where the deck has a minimum size rather than exact size, allowing flexibility in sideboard card swaps