It is indeed due to vote cheating in the past.
I don't think this should be changed, but you are right it should be written somewhere in the rules.
Yes, I can agree with that. Even though the user pointed out that if you really would like to win an election due to cheating, you‘d just have to plan a bit more in advance in order to be able to vote. But it‘s true. Like this, someone would have to register and log in more than 4 weeks later again to vote. Not register, vote and be gone right away....
So conclusion: short paragraph in the rules and everything is fine with me
Du hast nicht genug Geld, um dieses Gebot abzugeben!