That is true but then it applies to everything and you can't pick and choose which app to filter and which not (I exclude banking app for example), what level of filtering you want for each app (my phone is not rooted so there are some apps which will reject https filtering), and additionally I can quickly turn off and on filtering in the app for example when there's a need for troubleshooting why something is not loading etc. In short, with an app you have more control and access to stats: