I think that is more a resurrection of the department store and mega-corp models: if you do a bit of everything then the bottom falling out of one market won't

I think that is more a resurrection of the department store and mega-corp models: if you do a bit of everything then the bottom falling out of one market won't affect you badly as the other areas can soak up the temporary loss. Also, if you have positive name recognition in some areas this can benefit the others, and there is a passive advertising pressure of people using you for one thing seeing something else you have in store or linked to your name (where a more organic search to fulfil a need might be as likely to lead to a competitor as to you). The difference that might break this analogy being that with a mega-app there isn't really a diversity of revenue streams despite the diversity of products/features: it all comes down to stalking to be able to better sell advertising.