Why hot fix read me has the instruction to take a back up of DB
The hot fix manager in Pega 7 has the possibility to install the hot fixes either with Commit option selected or with un-commit option. As per this feature, this provides the facility to do a rollback of the hot fixes which have been installed with uncommit option.
Please provide a clarification why still the ReadMe of the Hot fix has the instruction to take a DB back up. As this involves an extra effort to do a DB back up or restore point for every hot fix we install.
It is unlikely, but possible for a hotfix to break the startup of Pega or break hotfix manager. If Pega is unable to start or hotfix manager isn't working properly, you would not be able to rollback the hotfixes. If this were to happen, the easiest way to recover would be to revert to a DB backup.