Why are you trolling? Like legitimately asking? What have these people done to you or why are you happy that people might get angry at you?
When people don't have anything better to do in their personal lives, they like to harass people who do. They could be out there doing something positive, but instead, they choose to be weirdos on the internet. I think that says it all.
It would be very hard to pull off in these times, considering there's so many eyes everywhere, and if people are able to point out which act is lip-syncing or not... It'd only be a matter of time until eagle-eyed and eared fans put two and two together. Especially when they notice their speaking voice(s) and their singing voice(s) aren't congruent. And if we're talking about actual dedicated fans who engage in the content religiously? They WILL find out.
If such a thing were to happen, they would need to find singers that sound very close to the idol(s) and it would be absolutely imperative that they nail their lip-syncing. This would take a lot of coordination and organizing, and they'd run a very high risk of someone from behind the scenes exposing them. That's just on your typical TV performances. Going on tour, it would make that even more challenging because now you have more possible liabilities to consider. What if the original singer gets sick? What if they decide to walk or go on strike mid-tour? What if the performer makes a mistake on stage like they trip or fall, but the singing isn't affected at all? There's so much that could go wrong.
A scandal like that is not only career-ending for all of the performers in question (save for the original singers), but it would put that company in jeopardy if not outright ending that company as well. That would be a complete violation of trust between the company and the consumers, and that's NEVER something to take lightly. It would open up several cans of worms because then people would wonder about the other musical acts within the company and their legitimacy. The only time I could sort of see this happening is if a tour is near, someone lost their voice/is experiencing difficulty singing due to health reasons and they don't want to back out so close. But even that is a big risk because again, it puts everyone into question, and they'd be much better off being transparent with the fans regarding the situation. People would be disappointed, but they'd understand. The last thing you ever want to do is lie to your consumers.
If a group debuted and ended up being exposed for this, the group would most likely come from a smaller company, because there's no way the giants would ever take such a huge and reckless risk like that. There's too much to lose, and why go through all that when you could just form a group with singers who can actually deliver?
