Comment # 1 on bug 1204467 from Andreas Stieger

No, updating all other packages could lead to unexpected problems that are
worse. By principle of least surprise this should be bubbled to the user to
resolve.

This returns a valid solution on a stock problem:
$ zypper in --dry-run plymouth{,-lang}

Find out what blocks the update and resolve that.

Assiging to libzypp maintainers to close. I believe all transactions that have
any conflict or ambiguity should only proceed if we have have a user-informed
resolution, or bail out.