As Mohenjo-daro prospered, the gap between its richest and poorest households actually shrank. Its shared infrastructure, fair trade systems, and lack of powerful royal elites suggest that equality may have helped fuel the ancient city’s success.
its still quite speculative to draw the conclusion that it was truly egalitarian or lacking in powerful elites
Shouldn't it be that we need evidence that there were powerful elites in order to conclude that it was not/less egalitarian? If at this point we have no evidence of elites, we shouldn't simply assume they exist. The weight of existing evidence in M-D so far indicates little concentration of wealth and more public works projects. Maybe they were blessed with the most benevolent, publicly-minded and progressive rulers and elites in the ancient world, but we can't say that until we have evidence of them.
Considering the lack of similar examples in the archeological record...
I'm no archeologist, but there are other examples. Harappa is another Indus valley civilization characterized as egalitarian. Catalhoyuk in Turkey has also been interpreted as a more egalitarian society.