This is the mistake that Adobe makes and where Affinity could have a competitive edge - if it chooses not to follow Adobe's lead. The reality is most people designer posters and simple print pieces in Adobe Illustrator or Affinity Designer, not InDesign and Publisher. Those tools can be useful for very long documents like books and newspapers, but they're far too limiting to to be useful for most design. Text columns and threading aren't cumbersome or difficult tools to produce - just include them in the Designer application and you'll outcompete Adobe. Doing the same dumb things Adobe does (dividing up applications unnecessarily) isn't going to win converts.
Forcing people to switch excessively between applications is a huge hassle. Serious designers need to mix and match textures, type and images seamlessly. Affinity Designer's superior raster and masking tools give it an advantage over Illustrator and it's why I'm giving it a chance. But finding out that Affinity is not following this strategy across the board makes me want to just back to Adobe products, since at least I know them already.