They really couldn't all happen on their own. They wanted to write more code in C#, so of course it makes sense that they'd start with the new systems they were making for the ECS. To support being able to write more in C# they developed the burst compiler. And the jobs system is a huge part of the way they developed their ECS system.
DOTS really just means Unity ECS plus a lot of other stuff that exists mostly to support ECS, and some stuff they've wanted to do for a while but it makes sense to add now since they are changing so much of the public API anyway. They brought Mike Acton in and "Data Oriented Technology Stack" is just all the stuff they needed/wanted to realize his goal of making things more performant/data oriented.
They were just calling all of their re-architecture ECS until a little while back, but it was kind of weird and ECS is already a severely overloaded term.
Would you be less upset if they called it "The re-architecture" instead of coming up with a convenient name for the new way of doing things?