[avsm]

And those lightweight VM base images are possible because Docker applied a downward pressure on OS base image sizes! Alpine Linux doesn't get enough credit for this; in addition to being a great base image, it was also the first distro to prioritise fast and small image creation (Gentoo and Arch were small, but not fast to create).

[imtringued]

There's also the part where you have a much easier time building alpine packages inside a container rather than a VM. There is no docker run equivalent that lets you quickly run a shell script inside the deployment Linux distribution to build the package.

[kgwgk]

Maybe in that alternative future of massive block devices some downward pressure on image sizes would have been applied just the same.

[avsm]

It's not as easy; a block device has to be bootable and so usually bundles a kernel (large). And because the filesystem inside is opaque, you can't do layering like Docker does easily via overlayfs and friends. libguestfs does a heroic job of making VM images easier to manipulate from code, but it's an uphill battle...