It goes like this: Imagine that, as a government, you want to be able to reshape a narrative in the future, of the type "Oceania had always been at war with Eurasia".

For that, you need to be able affirm, without to much push-back, that the view you are trying to re-model, has always been as you claim it was. This implies that there are not too many "historical traces" people can uses are references to successfully argue against your reshaping.

What's on the internet is not too difficult to deal with. You can rely on SEO rigging and AI slope to drown any useful information in an almost unpenetrable sludge of garbage. Worst case, you can use the pretext of child protection to pull down some sites or go after some hosting companies keeping information you would like to see removed.

What's left is the personal records of your citizens. That's a bit more tricky, because it is less easily accessible. It might even be encrypted enough for it to be a nuisance.

Now, if you can convince users that they are "sparing the environment" by deleting their data, they might slowly make it a habit to delete information they don't use that often. Old pictures, invoices, etc. And in the long run, also delete any tangible information that could be used to make your government accountable for the degradation of quality of life, life expectancy, etc.

Even better, by deleting old pictures and memories, you also delete, at the same time, the association thoughts that might come with those resources. A picture at a train station might remind you of a certain convenient train connection that existed in the past, and got removed after privatization. Or a picture of a ticket fare could remind you how disproportionately prices have increased with respect to wages, etc.

Just a far-fetched thought..

I very, very strongly doubt that.