Microsoft is now migrating away from the bare metal Hyper-V server in favor of Azure Stack HCI which is not generally suitable for every scenario. Hyper-V server competed with vSphere which has a 75% market share which is why Microsoft has abandoned the product.
Now that servers with more RAM, a single machine can run several Linux instances or remote desktop systems. This is driven by multicore servers and the availability of 64GB and larger DIMMs.
Azure uses Hyper-V extensively for running web servers and virtual machines.
Web hosts today can run a lot of websites from a single server. Given a 2TB SSD, at least 250 WordPress sites can be hosted. With a larger SSD there can be thousands of instances of WordPress. SSD servers are widely available. Hard disk servers are also widely available. Blade servers are common with larger web hosts who pull data from SSD or hard disk depending on the service tier.
Many older webservers are using hard disks which are cheaper to procure. These tend to be too unresponsive for general WordPress users. Hard disks are fine for CDN image hosts etc.