Nancat, I would have said that the Lib Dems are only calling to revoke Article 50 because they have not been able to secure another vote on Brexit (which they have campaigned and asked for since 2016).
Because of all the lies and irregularities in the referendum campaign, and because of all the information that has since come to light, a People's Vote is a sensible reconfirmation before taking such an irreversible step.
Article 50 would only be revoked if the Lib Dem party were in government, and if that were to happen it would be because the majority of people voted for it - therefore totally democratic.