Does anyone reuse /boot or /var partitions ?

[Chris Murphy]

Historically /boot is owned by a particular OS installation whether
its a separate volume or a directory. I think it's sloppy as hell to
share /boot without a spec like bootloaderspec to define the exact
location each OS installs its stuff into. It's completely sane the
installer team wants to explicitly do away with shared /boot unless
there's a spec. And there is a spec there just isn't enough momentum
to support it apparently.

/boot as a directory achieves both space savings and separation of
boots between OS's. Where /boot is on a LUKS encrypted volume is the
one exception, which although GRUB2 supports that, it's not
automatically configured for the user and would need installer support
to do that configuration to make it a sane option.

Chris Murphy