There is nothing at all constructive about saying we should let migrants drown in the med or that all Muslims are subhuman scum.

Again, stop with all these strawman arguments. That is not how it works out in practice, nor are those people even allowed to comment. At this point I start to wonder if you ever read /r/europe in the first place.

It's really quite easy not to be banned from a subreddit if you're not a total shit.

At this point it will come down to personal experiences anyways, but I've seen the opposite of that on /r/europe. Fortunately I've never been one of David his victims (maybe I'm still in his definition of 'acceptable' hmm?), but there were dozens of examples of innocent people being banned on /r/europe when he was still a moderator there. To say that it is 'really quite easy' is not how I've seen it works in practice under his 'guidance'.

The default subs that Davidreiss helps run are actually good. Unlike most other defaults they're not filled to the brim with bigots or shitty low effort memes. /r/history and /r/historyporn are two of the best large subs on the website, only really beaten by /r/askhistorians and /r/askscience. All use heavy handed moderation and all are better for it.

Then there's of course the niche factor you need to consider: all those subs you named are constricted to a select field of science and already have strong academic conventions about how 'truth' should be exposed. The same does not apply on a more generalistic sub like /r/europe, where there is no clear goal or mission except for 'things related to Europe'. Moreover: /r/europe like /r/worldnews is drenched in political debate and silencing another faction - instead of striking that faction down with proper arguments - has always been controversial.

I understand the comparison, but it is flawed on those grounds.