They can serve a purpose or just be a reason to show off. One of my favorites is in John Mayer’s song gravity. There it feels like a nice break and it makes the song feel that much more relaxing. However in some songs it can go on for too long and feel a little overwhelming and just bad. It also depends on genre where a heavy metal song might have a lot of guitar solos because that’s the style, a hip hop song with one would probably feel out of place. This just my opinion and overall guitar solos are quite enjoyable