Not sure what you think you're describing with ''fleets of personalised apps'' but it sounds a lot like algorithmic homepage feeds and recommendations. We already know there is a lot of toxicity in that idea as it breaks down the common reality and common experience of an app, website, and of your corporation. You will need to keep a tighter rein on these variants, rather than less.

Facebook's personalisations ended up recommending hate speech, YouTube created extremist pipelines. TikTok promotes fake conspiracies.

Many websites already experimented with deep user customisation of the interface. It was a nightmare in terms of usability, troubleshooting, maintenance, performance & aesthetics. And that was AFTER the era where people just made their own websites. What, in a concrete sense, could any tool do to solve those problems as well as provide a net benefit, rather than simply commit a rehash?

Far from being unknown, we - humanity as a whole - already know a lot of rules about this sort of stuff. What we need to do is bring those lessons forward into the next era, rather than pretending everything is brand new just because some tools got better and learning everything the hard way. Again.