Reddit accounts have positive karma upon creation, and posts which are both heavily upvoted and also heavily downvoted increase your karma overall due to a cap on the number of downvotes that can impact your karma. To offer an example of this, the most heavily downvoted Reddit comment of all time was this one by EACommunityTeam, which received 668,000 more downvotes than it did upvotes. Clicking on the link to their profile will show a handful of comments with hundreds or dozens of net upvotes, and about as many with several hundred thousand net downvotes. Their comment karma is positive and a five-digit number.
There was a time when bots advertising knock-off merchandise such as t-shirts were taking up a considerable amount of our time, and also making r/LastEpoch look unmoderated - nobody likes going to a subreddit and seeing spam from bots on the front page. The introduction of a modest karma requirement to post in our subreddit resolved that problem overnight - most bots have in the range of +5 - -5 karma, and so their spam is removed without ever being seen.
I am genuinely sorry that this filter is impacting you, however I have to respectfully disagree with your claim that it is a bad idea. The metric relied upon by the filter is biased in your favour. The subreddit has nearly 10,000 Redditors subscribed to it, receives comments and votes from people that aren’t included in that number, and I believe this is the first time a user with negative karma has contacted us regarding it. The filter does a tremendous amount of good.
Every Redditor occasionally has comments downvoted, and I can appreciate that this happening several times right at the start may taint one’s impression of the system as a whole. That said, I do think you may have been overly quick to judge it. Just spending some time in subreddits relevant to your interests and being respectful when posting will result in the majority of your posts being well-received. This is how the system works and won’t take long at all.