I largely subscribe to what is described here, and believe sincerely that any piece of work should be an opportunity to do a little bit of cleanup.
Though, one counter-argument in favor of putting refactoring tickets on the backlog is that it can be useful to make the cost of cleaning the codebase more visible to the higher-ups.
This is especially interesting if each sprint you organize to take up the feature tickets AND the refactoring tickets at the same time. If you work in a place that refuses to pick up the refactoring, then indeed the "hidden" approach described here is probably a good way to go.
i had the privilege of working w/ some incredible eng leaders at my previous gig - they were very good at working both upwards and downwards to execute against the "50/50" rule - half of any given sprint's work is focused on new features, and half is focused on bug fixes, chores, things that improve team velocity.
Though, one counter-argument in favor of putting refactoring tickets on the backlog is that it can be useful to make the cost of cleaning the codebase more visible to the higher-ups.
This is especially interesting if each sprint you organize to take up the feature tickets AND the refactoring tickets at the same time. If you work in a place that refuses to pick up the refactoring, then indeed the "hidden" approach described here is probably a good way to go.