I agree. But CHR is a general radio format that evolves as the music evolves. The artists change, but as long as the music is popular, it gets played regardless of musical genre.
Alternative is a genre based format that has had a lot of trouble trying to evolve. It's a niche of a niche. It's a subgenre of rock that was at one time very big, but has fallen on very hard times. Its fans want it to remain what it was, but it hasn't.
This subgenre has now developed subgenres within it, making it even harder to attract a sellable audience. KROQ is trying to latch on to the most visible part of the subgenre. So far, it's not doing very well. We'll see what happens as the station is able to hold outdoor events.