You could use an ad detector app to scan installed apps and know which ad networks they use. It's a facade in my opinion and to try and maintain relevance, the developers of those apps are using every idea they can think of to make you keep the app even though you don't need it at all. Oh how considerate of the manufacturer to include a space freeing app. To the unknowing user of such a phone, the app seems like such a savior. Some time ago I saw a lot of budget phones (with very little storage space to spare) come with this app pre-installed. The app may list your personal videos under 'large files' and mark them for deletion for example, and if you're the type that love a one-click-fix-all 'solution', you could effectively end up screwed. Furthermore, if you're not careful with those apps, you can end up deleting stuff that you would like to keep. Unless in this day and age you're using a dirt cheap phone with less than 16GB internal storage, you have no use for such apps.
A month ago I bought a budget Redmi 6 phone for my cousin at $100 and it packed 64GB of internal storage! The 32GB version is even more affordable.
Such apps may have had some use back in the day when storage space was very limited on mobile devices, but that is really no longer a problem.
