You absolutely can run agents on a regular VM. But if you want to build multi-tenant and multi-agent systems with strong security boundaries, then having a VM or MicroVM per agent session (or session with a group of agents) really simplifies things.

When we did AWS AgentCore Runtime last year we introduced session isolation, with MicroVMs per session. You can think of Lambda MicroVMs as the same stack, but generalized to fit a larger number of application patterns.