Positives of downvoting - I get it, it filters out the non-sense. Negatives of downvoting - Leads to herd and mob mentality - "Oh this is downvoted, I must also think this is bad since others thought so as well. Plunk, another downvote! Take that!"
Especially right now when we have intense polarization and people are pulled away from centrist, ideological and sound perspectives into narratives, biases and prejudices.
I've raised this before, but IMO - Downvoting does more harm than good in the long term. Short term benefits are that we get rid of trolls, rude people and actually false information.
There are also laws against using data for some other purpose than it was collected for, but they're less well enforced, and it's pretty frequent that a sneaky T&C clause let's them use data for something else.
And since they don't believe they will get caught (probably due to their track record with getting away with everything) there is no reason to care either.
And they don't have to be as blatantly stupid to send ads to the numbers, they could do as facebook, use it for a shadow profile.
if(IsEUCitizen()) {
...;-)
By all means, use a throwaway number for signup / 2FA setup.
Does the phone number serve another purpose besides security? If it does, then any assurances during sugn up that the information provided will only be used for the purposes it is disclosed would be false. Knowingly false statements made to induce someone to sign up could be considered misrepresentation.
(Facebook has been caught doing that.)