In the past, companies had their own physical exchange in place in the premises and needed a separate firewall to maintain safety. A single exchange was quite vulnerable if something ever broke. You had to purchase service agreements as defined setup times and service levels. Service agreements were required to even be able to call the support and then you had to pay for the due time.
For a cloud service, security is one of the most highly prioritized issues because the entire customer base is down if a malfunction ever happens. So as a customer, you get a much more costly and safe solution than what you could afford to prioritize as an individual customer. Additionally, you can be sure to get maximum attention if an operating outage ever happens, as a malfunction affects an entire customer base, without having to purchase additional service agreements.