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If by everyone you mean some people here and there, then sure.

Do you find it sensible/useful to have a separate app for a core function of the main app? For which they still continue to have a dedicated button in the app for that purpose, only to now bounce you to a complete different app?
 
Do you find it sensible/useful to have a separate app for a core function of the main app? For which they still continue to have a dedicated button in the app for that purpose, only to now bounce you to a complete different app?
Well, there are changes that are happing with that: https://www.macrumors.com/2016/10/03/facebook-e-commerce-marketplace/

And as for usefulness, another post from the thread related to the above mentioned article speaks fairly well to it:
People complain about Messenger and Facebook as separate apps, but I love it this way. I don't have Facebook installed in fact.
 
They just moved the dedicated chat button to the top left, next to the status bar. Still does the same exact thing of bouncing you to the silly secondary app. But I guess if you like it I get your point.
 
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