An opposite approach is hosting multiple services per host. This helps to optimize the utilization of the machines but it also comes with some drawbacks. First of all, different microservices may require different optimizations, so hosting them on a single host will still be impossible. What's more, with this approach, you lose control of the host allocation, so the problems in one microservice may cause outages in a colocated microservice even if the latter would be otherwise unaffected.
Another problem is the dependency conflict between the microservices. When the microservices are not isolated from one another, the deployment has to take into account different possible dependencies. This model is also less secure.
