- No concept of commerce, used a barter system for their economy
Barter systems only exist in the modern world when systems of capital collapse and were essentially invented as an ancient fact by Adam Smith to justify his works. If markets predated the state, that gave some credence to the idea that the emergence of capitalism was a good, natural thing.
Modern research on what the Quechua and other local people of the time actually did has largely been tainted by that and is often biased towards attempting to prove that point a priori.
If you look at contemporary accounts, it was similar to a lot of pre-nation-state systems in which land was largely used as-needed based on loose precedent rather than owned and leased under a codified judicial system, gift-giving was the primary method of exchange for luxury and the community largely provided for the base needs of the community.
Inca Garcilaso de la Vega spent a lot of time explaining this to Europeans in his Royal Commentaries of the Incas. They had trouble understanding living outside of a newly developing system of markets, the nation-state, and capital. We do as well in the modern world were those things are all the more entrenched.
Here are a few chapter titles as a taste:
"Gold, silver, and other objects of value were not offered as tribute, but as presents."
"They supplied clothing for their subjects; there were no beggars"
"The laws and ordinances of the Incas for the benefit of their vassals"
That's not to say that it was all good, for example the Sapa Inca could force anyone within Tiwantansuyu to perform labor for them as they were the head of royal family and, because of this, divine.
It is however, not barter.
- The Inca obviously had a massive technological disadvantage
I contest that idea, and so did many writers of the past about many indigenous peoples. Inca Garcilaso de la Vega dedicates a whole book of one of his texts to describing marvels and oddities of technology from Cusco.
They didn't have a massive technological disadvantage; they just didnt conduct war at the scale Europeans did, so they never really needed to develop those tools of war.
You don't need to smelt bronze or iron if you're not waging war. The stuff holds an edge and you can make a lot of it fast, but that's not appealing to anybody that doesn't suffer the wars Asia, North Africa, western Africa, and Europe did. Making pottery, textiles, and tools from much more easily-extracted resources makes much more sense in the world of medieval and renaissance Peru, and their technological development reflects that.
Were the kings and queens of Spain less advanced than the Sapa Inca because they didn't have quipucamayocs advising them?
Edit to note
: in the gift-giving chapter above it relates to the gift-giving of peasants, the Inca, and their vassals to the Sapa Inca and his governance, but the chapter speaks about how these things are so common and their ownership within the society