Comment by jsnell

The duration you'd need the memory for is a couple of seconds, during which time you're pegging a CPU core on the computation anyway. It is not needed for the entirety of the browsing session.

Now, could you construct a challenge that forced the client to keep a ton of data in memory, and then regularly be forced to prove they still have that data during the entire session? I don't think so. The problem is that for that kind of intermittent proof scenario there's no need to actually keep the data in low latency memory. It can just be stored on disk, and paged in when needed (not often). It's a very different access pattern from the cryptocurrency use case.