Primarily they do not monitor the status or health of the connection to the remote file-system. You can end-up writing GBs of data thinking everything is working fine only to realize upon program termination all your data was lost.

There are no python alternatives that work, while the best method of doing that is using rclone which is written in go (which is the back-end also used for rmount). However the only way to troubleshoot broken connection or issues is by going through the logs of the library and a lot of manual effort (which is what rmount primarily does for you out-of-the box)

Part of the reason of all the issues mentioned is that rclone uses Fuse file-system and as such from several layers of abstraction (Fuse-> Go-> RClone-> Python) it becomes more difficult to diagnose and deal with failures. That is what rmount tries to do.