why doesn't spring-boot listen to the logging.path variable?

From the documentation:

If you want to write log files in addition to the console output you need to set a logging.file or logging.path property

Spring boot considers either file or path property, not both.

This page has all combinations of file and path properties.

Variables path and file can be used simultaneously in the following ways (application.yml):

logging:
  path: /var/log/
  file: ${logging.path}app.log

As a result, spring-boot will keep a log in the file /var/log/app.log