I think:
1/ There are no official Russian translations, so whether or not there are Russian translations ahead official English translations doesn't matter. It won't disincentivize people from buying official English translations (except Russian English speakers).
Additionally, just because Russian sites do it doesn't mean everyone can and should do it, too.
2/ Your argument doesn't take into account the people who buy official translations because they cannot wait for official translations to be distributed. These people won't buy official translations if unofficial translations are out before official ones. We don't have enough info on the proportion of this category of readers to the category of readers who buy simply because they want to support the author. It might be the case that the former is not of the majority, and so posting fan translations on this website doesn't affect profits at all. Since we don't have statistics on this, and we will never do, perhaps we shouldn't take chance with it. The point unofficial translations opposers is making here, thus, is that we shouldn't risk making what we are doing even worse. You can think of it as, "stealing little is bad, but not as bad as stealing everything."
For example, think of the original uploader who has been uploading fan translation. Would she continue to buy official translations, knowing that unofficial translations have already been uploaded? Keep in mind that many uploaders here also upload for likes and followers on Instagram, so with fan translations circulating, there's no point in purchasing and uploading official translations anymore. (i'm not saying painter of the night uploader uploads for attention).
Disclaimer: I have yet to take sides on this, but I do see other people making argument here that does not directly counter the complaints about unofficial translations. I'm fine with waiting one or two more weeks for the official translations. I'm already leeching off others anyway.
With this let us just put this matter to rest.
This site has constantly gotten into trouble for uploading fantranslations which were ahead of the official ones. The authors get mad when they find out about official translations being uploaded illegally but they usually don't do much. However, when they find out about fantraslations being ahead of the official ones it gets dangerous for the site, simply because all the people who buy the chapters to read it first have no reason to do it anymore.
Besides, fantranslaters who work on officially licensed webtoons usually don't do it for long. PotN might go on for another year and to actually justify making your own translations you have to be ahead of the official release, otherwise it's pointless. That's a harsh schedule for someone who's doing it for free hence why most people give up after a while. And then you're left with waiting for weeks for the official translation to catch up.
The russian sites already have translations up to chapter 37... yet we are limited to official English releases only. I don't mean to sound ungrateful, but I don't understand why we can't upload fan translations here.
1) This entire site is illegal.
2) -most- people here weren't going to buy the official translation anyway.
3) people who want to support the author will do so anyway regardless of pirate sites.