Because the server is entirely abstracted away from computing applications that do not require direct access to the underlying hardware and only have to produce a computation result.
Conceptually, «serverless» is a reincarnation or an evolution of the VAX VMS style cluster computing: applications running on VMS clusters see the cluster as a single computer. Adding a new cluster makes the cluster more powerful, yet the app continues to see the cluster as a single computer. Cluster nodes can be geographically distributed, appear and disappear without the app noticing it. So, serverless apps, whilst technically running on a server, actually run somewhere (on a cluster node) but the app does not know it and does not care about it.
So «serverless» in the cloud takes the concept further, slaps on the automation and makes it more accessible to mere mortals, it scales (almost) indefinitely and completely transparently from the application. It requires no setup and is easy to use (setting up VMS clusters requires an experienced and knowledgeable systems engineer, for instance).
We can agree and disagree on the semantical correctness and richness (or the lack thereof) of the term «serverless», but it has already caught on and has evolved to mean more than just cloud serverless functions.
Conceptually, «serverless» is a reincarnation or an evolution of the VAX VMS style cluster computing: applications running on VMS clusters see the cluster as a single computer. Adding a new cluster makes the cluster more powerful, yet the app continues to see the cluster as a single computer. Cluster nodes can be geographically distributed, appear and disappear without the app noticing it. So, serverless apps, whilst technically running on a server, actually run somewhere (on a cluster node) but the app does not know it and does not care about it.
So «serverless» in the cloud takes the concept further, slaps on the automation and makes it more accessible to mere mortals, it scales (almost) indefinitely and completely transparently from the application. It requires no setup and is easy to use (setting up VMS clusters requires an experienced and knowledgeable systems engineer, for instance).
We can agree and disagree on the semantical correctness and richness (or the lack thereof) of the term «serverless», but it has already caught on and has evolved to mean more than just cloud serverless functions.