I call bs.
there are plenty of third party software published NOT on the App Store that I download and use every day, and they are NOT limited to the Apple developer platform.
Brave, Chrome, Firefox, Drive Genius, various antivirus programs.
You're being lazy at best, disingenuous or outright misleading more likely.
I've used TurboTax for decades, keep this up and I'll switch along with the thousands of others who have left Intuit.
Charles
