Speaking ahead of this weekend's live semi-final, Bo claimed that the BBC's strict rules on publicity prevented the winner from getting any hits.
Last year's champ Leanne Mitchell's debut single - a cover of Whitney Houston hit Run To You - missed the top 40 altogether, while her debut album failed to crack the Top 100.
The BBC's rules mean that bosses aren't allowed to directly plug the artists on the show, something which The X Factor does constantly for its stars, past and present.
“I think it was really hard for Leanne after she won," Bo said. They just put out a single and didn’t really advertise the fact that it was out there and available to buy.
“Normally you would have a huge marketing campaign before a big release. But you can’t do that when you have won The Voice."
She told The Sun newspaper: “Being part of the BBC, they can’t be seen to do that. They have far more restrictions. If you look at The X Factor, they are allowed to heavily promote an artist or a singer.
“Because of that, they almost always have at least one No 1 single.”
Meanwhile, Bo suggest that she was happy to have lost out in the final last June.
“Personally, I think it is better to be runner-up as there’s less pressure to have an instant hit," she added to the newspaper.