It is rooted in a lack of imagination. The entire argument is basically because this network does not do exactly what Cisco and the big VPN vendors with large enterprise deployments and bare-metal machines and thousands of end node clients it will not displace them.
That’s like arguing that the streaming will not displace CDROMs, because streaming cannot be rotated in a disc drive at a sufficient speed. The author acknowledges containers, but disregards the growth of zero-trust-networking and evergreen deployment models.
Technologies like Tailscale and ZPA, Docker and Snap, and immutable operating systems are being quickly adopted. These change the equation to the point that traditional approaches around ZScalar may feel as obsolete as a 5.25 floppy in a CDROM world.