That's pretty much how it used to work.
The main reasons why it changed are:
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Space, as a connector is slightly bigger than a soldered connection, and the battery itself has to be slightly bigger and stronger too to be safe to transport and handle without being protected by the phone's case.
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Water resistance; it's far easier to make a phone's case waterproof by just glueing the whole thing shut than having to use seals and gaskets and such to make it possible to open and close it at will.
An old forum I used to frequent had a downvote system that required you to specify a reason for why you felt that post or comment required a downvote. That reason (and the account that submitted it) was visible to the person whose post got downvoted and to the moderators, but to no one else.
It still worked well for filtering out troll posts and spam, and legit posts were almost never downvoted as you couldn't do so fully anonymously and moderators could take action when you abused the system.
I could see this becoming highly impractical when communities become as huge as on Reddit though, but for a smaller forum that one had a few hundred active users it worked really well.