I'm honestly curious about this remark.
If Modern apps today were as limited as they were in Windows 8 then I'd wholeheartedly agree with you. But I actually find Modern apps in Windows 10 to be quite usable now that they can be freely resized and managed like any regular application.
I personally use several modern apps on a day to day basis, namely Mail, Calendar, Finance, Reader, Calculator, and the Office apps (in place of the full suite that I no longer have installed, saving several Gigabytes on my SSD), and I really struggle to think of any glaring issues that would make someone so vehemently condemn this entire class of apps.