What is the advantage of using a stackable Hub? Why it's important in Fast Ethernet?

Only two 100Mbps Hubs can be cascaded together, so the user counts are also limited. The stackable Hubs which are stacked together are a large Hub logically, so in Fast Ethernet, you could have two stack of stackable Hubs, which will increase the user count. The rule for Fast Ethernet is to STACK the Hub, instead of cascading Hubs.