Is the analogy of paper money to gold and silver incorrect, and is usury (riba) limited only to the six categories mentioned in the Hadith?

Most contemporary scholars hold that paper currencies are subject to Riba (usury) by analogy with gold and silver, because Islamic law applied Riba to them due to their function as a medium of exchange (prices for things). Paper currencies have replaced gold and silver in circulation, thus taking their ruling. This is supported by Imam Malik's view that Riba applies to "fuloos" (coins/currency) if they become a recognized medium of exchange, even if made of leather. Shaykh al-Islam Ibn Taymiyyah and Ibn al-Qayyim affirmed that the reason (illah) for Riba in gold and silver is their "monetary function" (thamanīyah), which is present in paper currencies. The Islamic Fiqh Academy has affirmed that paper currency is a standalone currency, having the same ruling as gold and silver regarding the obligation of Zakat and the application of both types of Riba (al-fadl and al-nasī'ah), and that each paper currency is considered a different class. This view is held by major contemporary scholars, which states that paper currencies take the ruling of the two precious metals (gold and silver) in all Riba-related rulings. Furthermore, Riba is not limited to the six categories mentioned in the Hadith but extends to everything that shares the same underlying reason (illah) for Riba.