The Internet Computer blockchain network is hosted by special node machines, which are hardware devices that are dedicated to the task (thus creating a sovereign network). This is conceptually similar to how the internet is hosted by network routing devices.
Traditional blockchains are different. Their network nodes are created using simple software, which interacts with other nodes and maintains a copy of blockchain state. Today, software programs are very easy to spin up on cloud computing "instances" using services such as Amazon Web Services. A consequence has been that the majority of their nodes are typically cloud computing instances. Because these can be spun up in an instant the investment required to create or destroy a node is minimal (notwithstanding any cryptocurrency stake that might be required to add a node to the network).
A grave risk with these kinds of architectures is that control over the blockchain network is handed to a small number of giant corporations. These corporations might decide they must switch off the nodes, owing to changes in regulation, or competitive threats, or malicious insiders might use their access to the physical cloud infrastructure to steal keys, or otherwise disrupt the networks.
These issues do not exist with the Internet Computer, because it runs on a sovereign network.
Every node in the Internet Computer network is a dedicated physical device, called a node machine, which is run by an independent node provider, typically from rack space in an independent data center. The nodes cannot therefore be switched off or tampered with by a small number of corporate cloud computing service providers.
While this is an important advantage, there are other technical reasons that special node machines are required to participate in hosting the Internet Computer network. The node machines are built to standardized public hardware specifications. This means that when the network is under load, they do not fall behind other nodes inside the same subnet blockchain, which statistical deviation the network's decentralized governance DAO might notice, and sanction them for.