Why is a single, scaled up backend required in products effectively have onky multi-tennancy? Software can be distributed onto client machines and be kept up t

Why is a single, scaled up backend required in products effectively have onky multi-tennancy? Software can be distributed onto client machines and be kept up to date. That was first solved with Linux packages managers more than 25 years ago. Before mobile we had a wide range of desktop operating systems with their own warts. TLS 1.0 was introduced in 1999. So cryptography already a concern back then. So what is really new?