You have to use heavier isolation mechanisms with those languages -- processes, containers, virtual machines. These are too heavy to support thousands of tenant

You have to use heavier isolation mechanisms with those languages -- processes, containers, virtual machines. These are too heavy to support thousands of tenants per machine. Edge locations are typically smaller clusters, and you typically want all your customers to present in every point of presence, so you need to pack them tighter. V8 isolates are light enough for this to work and be cost-effective.