I don't know what channel you are listening to, but in general there have always been musicians (and bands) writing their own music as there were have always been musicians performing songs composed by others with lyrics written by others. Songwriting is about as dead as cooking.
From what I've seen, it depends on what you listen to. Pop, country, and R%B are largely written and produced by someone other than the performer (hence, they are called "acts"). Most rock/inde/actual "bands" will do their own writing 90% percent of the time.
With the fields dominated by acts, how people make a living gets even more convoluted. Some songwriters who regularly work in-house for a label get paid "advances" that are really more like salaries (regular monthly payments, sometimes considerably higher than the expected royalties). That's especially common for career songwriters in-house at places like Nashville. Young pop or hip-hop songwriters hoping to use it as a stepping-stone to become an act themselves might not get paid a salary.