Legacy seems to be missing from the comments. Before the advent of Cloud IaaS (Infrastructure as a Service) a very large ecosystem of On-Premise hardware and so

Legacy seems to be missing from the comments. Before the advent of Cloud IaaS (Infrastructure as a Service) a very large ecosystem of On-Premise hardware and software flourished. The question needs to be considered in the context of greenfield vs brownfield systems as the trade-offs involved differ drastically.