What new technology allowed hideyoshi and other shoguns to enforce such edicts over powerful daimyo landowners?

That would be gunpowder and firearms.

The gunpowder and especially firearms, changed the warfare in Japan during the Sengoku era which lasted from 1467 to 1603 after which the period of the Tokugawa Shogunate began. The first warlord to use then extensively was Oda Nobunaga who ordered 500 matchlocks for his armies. The firearms represented a huge tactical advantage.