
I agree to an extent about it being cheezy, but I believe if you put the same kind of time into it as you do into say mastering or mixing tracks you can get some amazing harmonies. Remember, harmonies are just a small part of what they do and should only come on for short periods. TC Helicon stuff also provides a built in sound engineer working away in the background. Imagine your trying to sing a modern song. Voicelive can provide Hardtune, Tempo matched Delays, Doubling Harmonies and Reverbs all for as little as one bar. Pretty cool.
I agree, if you have a dodgy / untrained voice, nothing can help except perhaps Autotune or a singing teacher!

Luckily, most punters don't seem to be able to tell a good from a bad voice

but even a good voice can sound grim without treatment live or in the studio.
Somewhere there is a video (poor quality) of me showing how I integrate VoiceLive 2 for streaming/live. It is time consuming and there is a steep learning curve learning to use a harmonizer well. Not something I can do live. It needs to be automated.
I'm happy to do another, better quality video if wanted, but it's a bit of a niche interest for BIAB forum members.