Workflows are not zero-cost, they have their own tradeoffs compared to microservices. State management / bootstrapping logic becomes non-trivial, execution order though easier to visualize is also slightly not deterministic, workflows are not as well suited for request-response style replies due to the latency involved in total execution etc (but I think they are great alternatives to async / background workfllows) - and shared underlying infrastructure means increased chances of SPOFs.
The state must have improved much since then. Also, adoption of anything new to require remodelling your application into a different paradigm must be worth the value delivered. For example, modular monoliths became popular because they reduced operational complexity by reducing # of pieces involved. At the time, that value prop vs effort involved was unclear to our teams IMO