The "commodity network" thing is kind of weird. I'd expect that to make a 10x jump when switches went from Fast Ethernet to Gigabit (mid-late 2000s?) and then nothing. I certainly don't feel like they've been smoothly increasing in speed year after year.
Although I'd expect more jumps than Fast Ethernet to Gigabit, it's true the consumer space is kind of stuck on Gigabit (with 2.5 GbE just becoming more common now). Datacenters have had at least 10 GbE for many years.
Datacenter speeds were a different part of the graph.
I thought about this some more and it might be referring to WiFi speeds. Those have been steadily increasing over time with the transition from 802.11b networks of old to modern WiFi 6. Of course WiFi only became a thing in the very late 90s/early 2000s.
It seems to be entirely based on NIC bandwidth, rather than the actual time it takes for information to travel between servers via ethernet or optics within a LAN.
I'm also curious about those slow 1990s SSDs.