The only way to achieve a fully functioning sideboard is to simply put in the work
Outside of these environments, Urza can still be quite good, as he generates 2 bodies for 4 mana, provides a mana sink with a powerful payoff when needed, and can even turn things like Equipment and Sapphire Medallions into tools to race ahead of your opponents while still employing their inherent value
I don't know of any lore that backs up my take on this, but the u makes them bigger or the o means they are smaller
Packs, boxes, and cases each offer a different trade-off between price, guarantees, and the odds of hitting what you want
For example, if a card's power level is no longer a problem