Really a bot ddos maybe but i am just guessing here.

I don't get, why many people so desperately need to hide posts. If you don't like, what is written, you can simply stop reading and proceed to the next message instead.

Hiding "unpleasant" posts does not make forum a better place. Precise rules and wise moderation do.

As for dealing with spam ads, only automatic spam-prevention and cleaning mechanisms can be effective.

It's clutter. And once you hid a post, it stayed hidden, so you didn't have to keep scrolling past it in that thread, even if you went back to an earlier part of it.
Think for example of back and forths between 2-3 users derailing a thread, or those who quote a lengthy post (possibly the OP) in full to add a couple of words at the end. Needing to keep scrolling past that, and remember each time which those posts are, is annoying and a drain.

I have seen DDOS attacks before and I assure you, it is not one.

1. Off-topic and meaningless discussions should be prohibited by rules and moderated accordingly.
2. Over-quoting can be automatically minimized by simple script.
3. You still have to analyze post before hiding it. However, it is moderators' responsibility to keep threads clean and communication polite.

QOL thing for me. I'm not obligated to read something I find obnoxious, annoying, etc. whenever I browse a thread. Plus I usually read a thread more than once so having to see the post multiple times is annoying. May well be emotionally immature, but my day is brightened if I can simply hide it.

I think Timboli mentioned a different script which works with the "former" downvote feature to hide posts. Jerkmuter:

https://github.com/Alaricus/JerkMuter

is also a cosmetic filter. It works similar to the use of uBlock Origin and the filter rules I mentioned earlier in this thread, see
https://www.gog.com/forum/general/users_using_blacklisting_scripts_on_this_site_gog_wont_lift_a_finger/post27
and
https://www.gog.com/forum/general/users_using_blacklisting_scripts_on_this_site_gog_wont_lift_a_finger/post29

Jerkmuter is probably more convenient than using these rules in uBlock Origin.

Meanwhile in the mentioned thread, this post

https://www.gog.com/forum/general_de/neuerscheinung_bxelb_7b776/post7

was reported here

https://www.gog.com/forum/general/spambot_report_thread/post14

and got deleted. Let's wait and see when the next spam post appears.

But isn't "cosmetic" what you want? Is the "additional downvote option" you prefer offering more than just cosmetics?

As far as I know GOG was already trying to blockj this specific spammer by using certain rules but without any success. So yes, he will always be back.

You use these cosmetic filters in your current browser. I think a server-side option to ignore users, report and hide posts is a better solution. You log in your account and you see everything according your account settings. This is the standard of other forums.

The best solution would have been the removal of the entire reputation system. In this way a downvote wouldn't have the rating effect anymore. The minus button could have been just a hide and report feature. This was also suggested earlier in this thread.

Yes...

Is not a sight of placeholders for hidden posts annoying as well? ;)

As you know this forum is far from being standard, up to date or even well supported ... or not broken. So we might just have to live with some workarounds as long as GOG is not replacing the whole thing with something better. I agree that it could be better but at least hiding unwanted posts with a workaround is still better than not being able to hide them at all.

The reputation sytem - at least the public rep (I am aware that there are still ways to access ones rep personally) - basically is gone already, isn't it? The only thing that still might need fixing is that those that were downvoted to hell still can't post links. Your solution of minus being "hide and report might" have been the best way but I guess it is not as easy to do than simply hiding a button... again, I doubt that many on GOG still know much about this ancient forum and how to change things ... if this even is possible at all.

I'm glad we can still +1 comments. Sometimes I don't know how to respond to a comment, so I upvote in lieu of an answer. My communication skills are very limited.

I agree, the workaround with Jerkmuter or uBlock Origin is better than nothing.

The whole reputation system is still active in the background. If someone uses really a bot to downvote, this user can still utilize the present javascript functions to downvote people. The "Low Rated" feature is not entirely gone. From what I've seen now in several threads is that there is not a bot active. Why? I don't know. One probable reason for this could be that several users actually downvoted each other. This is not good news. Currently, we see now that the reputation number and the downvote button is just not visible anymore. That is the current state.

Is that so? I mean, is downvoting via script still possible? Have this been tried?

I am aware that the rep has just been hidden from public but apparently that changed already something if bots are now inactive. Your assumption that bots have gone inactive because users downvoted each other does not make much sense to me tbh. Maybe the bots just stopped because

a) They don't work anymore.
b) They don't care anymore with invisible rep.