Seems pretty odd. The closest example I can think of would be maybe salesforce? Which basically, as far as I can tell, launches a whole new instance of the application (hosted by heroku?) for each client. I'm not a 100% sure about this, but i think this is how it works.
Not at all how Salesforce works, they take a lot of pride in their multi-tenant setup (for better or worse). Every org on a given instance shares the same application servers and Oracle cluster.
If I were to make a Salesforce competitor that’s one thing I would do differently, with tools like Kubernetes it’s a lot easier to just give every customer their own instances. Yes, it can take up more resources - but I cannot imagine the security nightmare involved with letting multiple customers execute code (even if it’s theoretically sandboxed) in the same process, plus the headache that is their database schema.
Salesforce has a lot of trial or developer orgs, which would be quite expensive if you tried to host them all as some sort of VM in a cloud hosting companies.
I assume most of them end up as a few rows in some set of DBs, which is far cheaper.
You can fill out a form and cause a free org to exist on their main site, so hundreds or thousands probably get created a day. It looks like they expire in 30 days, so if you spun up an app and DB for each it would get expensive quick.
As snuxoll writes, Salesforce does use a shared database with tenant_id (org_id) as a column on every table. You can read a lot about our multi-tenancy mechanisms in a whitepaper published a while back [https://developer.salesforce.com/page/Multi_Tenant_Architect...].
