They mention segregating their customers into separate /24s, and consequently having to assign an IP from every one of these subnets to the router for use by the customer as a gateway.
Is there any reason why they couldn't get rid of these by having customers set up a static route to the "primary" IP of the router (migration / configuration issues aside)?
For example, if I have IP 192.168.0.2/24 assigned to eth0, my routing table will have:
192.168.0.2/24 dev eth0 proto static scope link
192.168.10.1 dev eth0 proto static scope link