The seek time of a consumer-grade hard disk is said to be on the order of 10 ms. That's roughly the latency of a very high quality FTTH connection. Meaning that if you run a HDD rather than an SSD, a swap file in the cloud could potentially be faster than a local one (especially when you consider multiple reads/writes that could be done in parallel).

It's not exactly downloading more RAM but decently close to call it that for the joke.