I read some of the article and stil not sure what is so unique about eSIM compared to physical SIMs. Is routing user traffic through third-party infrastructure unique to eSIM?

The other risks mentioned are mostly rare edge cases

Removing the need to ship a physical SIM card created an entirely new ecosystem.

There is very little difference between a physical SIM from provider X and an eSIM from provider X (except that one requires an available physical slot and the other is a pain to move between devices), but eSIM allowed many new provider and reseller business models.

In practice, this means much more choice, much lower prices, but often also lower quality because everything is optimized to be as cheap as possible and often involves roaming agreements where your traffic gets sent on high-latency world tours.