One of the main ideas (of the Empire, not necessarily the religion) was that gold coinage came from God so that people could easily trade. Instead of everyone acquiring all the skills necessary for sustenance (farming, tool building, carpentry, etc) -- they could become masters of a few skills and trade the fruits of their skills in the open market. The idea was that doing so, humans could advance much faster. This was sort of God's secret sauce. So interfering with the market was like interfering with God. It was a no no.

One could argue that they manipulated the market by banning usury (interest bearing loans). However, before the Islamic Empire, interest was usually VERY high -- 60%+ per year was common. Debt was so cost prohibitive that the constant need for debt Jubilees was its own problem.

It's unclear how the Islamic Empire financed all these merchants without interest bearing loans. I'd love to learn more about how that worked.