An example: the HD must be replaced. So I send the iMac in for repairs and get a new drive. Instead of reinstalling everything, even with "automagic" MAS reinstalls, I simply press one button on the SuperDuper app.
Everything is transferred, bit by bit an identical copy of my old HD, onto the newly installed HD in the iMac. I restart, everything is as it was the day the HD crashed. All information, everything.
That's magic. That's impressive.
That app is not available on the MAS.
From my perspective the MAS is a failure, it is solving a problem that was never there (unless of course it is solving the problem that Apple didn't get 30% cut of every Mac app sold, in which case it is trying to remedy that)
I have always found software I need, just search the web.
In fact, I find it more difficult to find the app I need on the MAS; I can't look for apps by price, by specific function or expect all apps to be represented.
Furthermore, apps are all subject to Apple's review, redaction and cencorship - something I don't appreciate.
Finally using the MAS means I have to link my credit card to the Apple account, an important step for one to be "embraced" fully into the Apple ecosystem.