The impact on productivity also depends on the type of work. I suspect it's a net loss in the long run for things that require or benefit from deep work.
The transition from more waterfall-like projects to more agile-like, with feature-factory bitesize nibbles of work, seems to me to be predicated on less deep work. The unit of delivery is smaller, so it cannot be meaningfully transformative.
Personally I think it's a model that scales better (ie supports more developers being applied to a problem) but requires more brute force modularity to contain the lack of system design that comes from lack of deep thinking (and thus we get microservices).
The impact on productivity also depends on the type of work. I suspect it's a net loss in the long run for things that require or benefit from deep work.