Multiple video chats can saturate 20 Mbps up, but if they offered 200/200 it would be more than plenty. Them not offering reasonable plans in between a little to low and way too high doesn't mean that it couldn't exist, it just means that they aren't offering it, likely because they have paid your local government to prohibit any competition, allowing them to force a large portion of their customer base to use a more expensive plan than they need, because no one else is going to offer a reasonable one.