Perdue isnt comparing the difference of the area of conquest, but on the difference in the economic harms brought by each. Forced contributions imply that the region's existing economic structure is being exploited, exhausting the region's resources beyond its capacity, leading to long term economic decline of the region. The harms include the decrease in value of the region as a future source of revenue and when pressured more could even lead to revolts. This was why Perdue spent so many pages focusing on Qing policy in Gansu. As the province which bore the bulk of the economic burden for the Zunghar campaign, the Qing mostly bought things there at market price or carried their own ration. Gansu did not suffer long term economic decline and became instead more integrated with the rest of the empire. I've already quoted this point by Perdue and other historians of European warfare many times in this thread and people still seem to miss the point and go on a tangent because they do not digest the information before responding.Sure, a forced contribution was an improvement upon direct pillaging as a lip service to the rule of law and the recognition that totally devastating lands an army wanted to conquer was probably bad idea. However many wars the idea of conquest was not really central as national identities and borders were fairly established and scorched earth or harsh confiscations or direct pillage was still relatively common even during Napoleonic wars and the U.S. war between the States.
The criticism was that saying Europeans had not the capability to supply a relatively modest army is different than saying Europeans did not demonstrate this ability because it wasn't necessary. Even Qing only needed to demonstrate this ability in one campaign and it was the second try when the first campaign floundered a bit due to supply issues.
Also, the Zunghar campaign was hardly the only campaign where the Qing did that, the Qing also made strict orders to buy things at market price only in the Nepalese campaign of 1792, no instance of forced contribution was ever demanded. As I already demonstrated earlier, even in the campaign against the three feudatories in the 1670s the Qing did not exploit the locals after conquering them, but gave them years of tax exemption for them to recover. This could only be done because the Qing had a sophisticated and flexible bureaucracy in handling grain relocation.
Whether a state is nomadic is determined by its socio-economic structure, not by its geneology.Finally, I am not sure if it is a an accurate statement of Duzungar Khanate as the "largest and most powerful nomadic polity on earth" without qualifying it as 'at that time' because Qing themselves where the descendants of Jurchen and battled the Ming who were descendants of the Mongols sort of... really so much time had passed the the culture changed along with population sizes, technology, and relative power it was a different era.
A nomadic polity implies the ruling class wandered around grazing throughout the year, of which the Zungar state qualifies. The Jurchens were never nomadic, and even if they were they certainly settled down by the 18th century in Beijing. The Ming might have inherited Mongolian military and political institutions (in the same way the Mongols adopted certain Jin and Chinese institutions), but to imply that its a nomadic state is ridiculous.
As a nomadic state the Zunghars was the biggest military powerhouse of the era, they conquered the Khalkh Mongols in the 1690s, raided the Mongols of Inner Mongolia, conquered Tibet in 1717, and defeated the Kazakhs (who were also pressuring the Uzbeks) and subjugated large parts of their territory. The Kalmyks who subjugated the Nogai in the eastern Crimean steppe was also a small fleeing branch of the Oirat confederation eventually dominated by the Zungars.