To me it was the PC as he alluded to. But maybe for a different reason.

When PCs came out, first we had Basic (free) then Pascal and c came along. All were cheap compared to other languages. I do not know about APL, but IIRC, FORTRAN and COBOL both cost over $1000, the others were either free or could be found for under $200.

So, price won the day. I found Zortech c v1 (not c++) for $99 for my 286. That is where I ended up, and compared to Microsoft c I had at work later on, I thought it was just as good and in some cases better (disp_* libs).

When I went to Linux, back then it was c/c++. For some reason at the time, to me it seemed GNU had issues with providing APL and COBOL. I think that was due to academic snobbery. Now we have GNU APL and COBOL, but too little to late.