> Insofar as an OS is really a visible middleware layer that lets you run application software and manage files, I don't know if the lack of applications can be hand-waved away; that's a very tough nut to crack.

Yes and no. For most people, Linux is more than ready to be their only OS. There's no lack of functional software. I went through University only using Linux on my computer.

Edit - For example, most of the profs use LibreOffice, for sharing everyone uses Google docs, statistics and economics homework was done with R (Excel and Stata were the other options), all CS homework could be done on Linux. The only place I had to use Windows at all was a single course (Finance) where Excel was taught. I still just used LibreOffice then transferred the files to a school computer to make sure the output was correct. ----------------------------------

The only problem is that certain software still has the public's mind-share.

> But it's a much harder sell to someone doing, say, financial analysis or data modeling, where they absolutely must use Excel or SPSS.

Excel sucks and SPSS does run on Linux.