Do I miss something?

I cannot find hosters, who just provide a V-Server and allow you to run your Virtual Machines.

Where ever I try, I cannot install the VM-Servers into the hosted web servers since their (tweeked) kernels do not allow this.

I can find many hints about how to install webservers on VMware
or VirtualBox, but not the other way around.

What is the reason for this?