What does Shopify not do for you?
Bring you customers. It is a shopfront and a checkout, and every visitor is somebody you found and paid for.
Why the answer is what it is
It also does not give you a presence on a phone home screen, a notification channel you own, or a way to reach a past customer for free. Those are the gaps that most stores fill next, and they are what a mobile app is actually for.
What this looks like in practice
Shopify handles the parts that are genuinely hard and genuinely regulated: payments, taxes, order records. That is what the subscription is for.
The apps in the Shopify store are where the cost quietly grows. Six at twenty dollars a month is more than the plan.
Most Shopify performance problems are the theme and the images, not Shopify.
Where a mobile app comes into it
A mobile app sits on top of Shopify rather than replacing it — the catalogue syncs, and checkout stays Shopify’s.