From the announcement:
The premise of chiseled containers is that container images are the best deployment vehicle for cloud apps, but that typical images contain far too many components. Instead, we need to slice away all but the essential components. Chiseled container images do that. That helps — a lot — with size and security.
I'm glad that Microsoft is being mindful of how they are delivering .NET container images. However, this announcement feels like a large marketing effort to spin a failure into a win. The need to provide lean container images is as old as Docker itself, and Alpine-based images are synonymous with lean images. A very basic security measure in containerized applications is to not ship stuff you don't need. Microsoft's container images are indeed quite big without no good justification.
It's nice that Microsoft is fixing the problems they've been creating, but I'm baffled by the effort they are making to make believe this is something new or even a new concept.