if the votes are still +1 they didnt lose anything, aussming a comment was deleted because you think they lost a debate is just narrow minded and so singular focused. Does every comment on reddit have to be a debate? Can't something just add to the flow?
If the comment is deleted and +1 it can should be loggically infered they deleted for other, personal reasons. If you really need to know what was said, then use the redit internet time machine.
As for your last point, its all bullshit because someone can easily have several accounts and very easily manipulate their own history. This is reddit... the new wild west of the internet. There's no expectation to any control or privacy using this. If someone wants to delete something its theirs to delete. No matter what, they wrote it, and the platform (reddit.com) supports deleting comments. Until that changes you have no point. I used to run one of the larger bbs's in the region 22+ years ago, I had 5 phone lines and about 200 active and I had verified every single one of them face to face or over the phone. It was easier back then. Way too much effort to get a new phone number. No one here is verified, hell for all we know your /u/kingofkitchener