This is often very overstated. For example in government research labs there are often huge, critical pieces of software in both C and FORTRAN. I worked in one of these labs in the 00s and about 80% of my team’s work required running reports and simulations through a huge system written in C between the late 80s and mid 90s. Even generating plots for conference presentations was done in pure C with a special DSL tool that took in a static plot conf file and wrote raw postscript outputs.