Error in German and discussion is locked
In German 'Dative Case,' the sentence Die Katze gibt einer Frau einen Rock. accepts the translation The cat gives a woman a skirt. but rejects the translation The cat gives a skirt to a woman. Instead, it has to be The cat gives a skirt to one woman.
Why is the discussion locked?
This is a poor way to control spam...avoids solving the problem and hurts legitimate users in the process.
Public blacklists like AbuseIPDB can do wonders. Not only do they already list most of the worst offending IP's, but whenever you catch spam you decrease the likelihood of any more spam getting through from that IP.
And that's only one of many tools people have up their sleeve. There are CAPTCHA's for unregistered users, filtering of the content of the message.
Stripping tags for users with levels below a certain threshold also is a nearly-flawless way to eliminate the incentive / benefit for the spammers.
I have a huge spam problem with several of my websites, but it's easy to stay on top of if you're clever. After 8 years of running my site, I still have a zero rate of false positives and my anti-spam systems now catch 99.9% of the stuff I get submitted through web forms these days...and each message that gets through allows me to tweak the system, so it keeps getting better.
I posted a similar question, and a moderator (Christian) answered me: "The reason I locked that particular discussion was that we, the volunteer contributors, wanted to put pressure on Duolingo to do something about Pearson messing with our work. In that particular case, someone from Pearson changed the correct translation to something wrong.
Because of our protest, Duolingo has separated Pearson's course from our course, but some of Pearson's edits are still in our course. We're not entirely happy about that, but it is what it is."
I have encountered a number of these locked discussions and they bother me when I want to post a question. It's like, if there was some other problem, can't they fix / address the real problem, instead of hurting us users by a "baby-with-bathwater" type fix?
It's like, oh, we have a problem with school shootings? Let's just close all the schools...