No, but every app being open source (or rather Free Software, which is usually the case) can be supported easily by communities of users who can then bring it to tons of different architectures. That's why you get Evince on ARM, for example, and not the official Adobe Acrobat Reader.
The problem is not unique to open-source software.
I've been bitten this way too. It was a hardware/software product, small company made a neat little USB DAQ that became very popular. Bigger entrenched player bought the company and discontinued the line. Shortly after that they released their own product based on the ones they discontinued, but now it requires a much more expensive software package. Just because a commercial product is profitable does not guarantee its longevity.
Virtually every open source application is also Free Software, and vice-versa. The most common licenses (GPL, BSD, MIT, Apache, etc) fit both definitions.
GNU's not Windows, nor strives to be one. It's about bringing Free Software to whoever wants/needs it, not winning in popularity contest.
There's a lot of linux-compatible closed source apps I enjoy. Teamspeak, games, etc. Adobe Acrobat is one of the ones we absolutely don't need - there are many better alternative.
Just because Linux is open source, doesn't mean every app on it has to be. It needs popular apps to ever be a real desktop OS. No different than why Windows phone OS struggles today.