Another big issue for Quark was they were late to the market for software that ran on OSX …I think that could have helped them on the Mac Side of things. So, when Adobe came along and provided InDesign as a native OSX program that helped.
I know where I worked at the time we were heavy Quark users and never thought about switching until Quark dragged their feet on OSX.
I don’t remember a crossover issue with OSX. At that time though I probably had 4 macs in the office. One of them was a dual boot. We had the dually for a very long time after OSX came out. I still have one at home.
They also had terrible updating and pricing policies.
@PrintDriver I found this old forum post showing that QuarkXpress 5 only ran on OSX under “classic” but running it under classic (sort of “emulated” essentially) was “buggy” and it was odd that it wasn’t a native OSX program from the start,
And here is more here on the non native support issue.
According to wiki, “nDesign 2.0 was released January 2002 (just days before QuarkXPress 5). First version to support Mac OS X.”
It wasn’t until (I believe) middle of 2003 that Quark released a native OSX version. I cant find an exact release date on the internet. That may not sound like much, but this article explains the hassles of trying to run Quark in Classic mode.
In that year and a half people were too comfortable and happy to have InDesign that was better integrated with Illustrator and PhotoShop.
The folks in my corner of the industry also weren’t using Quark in depth, the way it was meant to be used as a publishing software. Probably didn’t notice any more bugs than used to dealing with Adobewares. I think Q5 was when they finally introduced the radio button that told the damn thing to send ALL the image data to the rip rather than just the size Q thought the image was supposed to be (ignoring the scaling factor being applied to it’s itty bitty artboard.) Q4 was the most stable piece of software I have ever used, after maybe Classic OS8.
I certainly preferred Quark files to Corel files back then. And Illustrator had, and still has, problems with large image placement. Don’t get me started on Pagemaker. There weren’t a lot of layout options back then. 
Sketch is best.
Adobe CC is the industry standard, in my opinion it’s too versatile to be overlooked. There are a couple of programs you could look into Affinity has a range of products that cost only a fraction of what Adobe asks 
Yeah, except none of them were actually doctors lol.