Mixing apps that add harmony

Hey All. I wanted to pass on something that I experienced this weekend. I went to go listen to a friend of mine who was back in my area performing as a solo artist, just a guy and his guitar. He's a good friend, but also one of many singer songwriters trying to make it professionally. He left northern Virginia a while back, tried to make it in Austin, TX in a band as a bass player, but ended up having to go back home to Sacramento, California where he's from. He said that the music scene was better there in California and money was getting tight trying to make it in our area, and in Austin. I got to the show a little late, summer stage at the brewery I work at from time to time. It was unseasonably hot and humid but I was looking forward to seeing my friend and hearing him perform. I noticed he had another friend there mixing for him from an iPad or Kindle of some sort. My friend is very talented and his performance was excellent. He played covers, some I recognized and some I didn't, but late in the set something weird happened. I started hearing harmony, backing vocals, but it was just him, one guy up there on the stage singing, no one else. My only guess was that the friend doing his mixing was using an app of some kind that added in the harmony to his vocals. Well it sounded good I guess, but you could tell it was some type of effect...not real if you know what I mean, so it hit me as unnatural. I'm not sure what I think about this little trick, and I doubt I would ever use this type of technology for myself. Has anyone else used this type of app? If so what do you think?  Anyway, I thought I would share.