According to Gunther Martens, research professor of German literature at Ghent University:
“Discussions in the Anglo-Saxon context have all kinds of face-saving measures,” he notes, “whereas continental debates pitch individual academics (and their reputations) against each other. At conferences, colleagues in English studies tend to ask questions, but they will always laud the speaker first. Americans are even more friendly…In the German context, a question is either a downright attempt to present one’s own view on the topic [or] a straightforward attack, meant to call into question the authority of the speaker. It is [considered] preferable to say that something is bad rather than to be implicit about it.”
Citing a colleague’s statement that “academic authority is the ability to offend someone”, Martens argues that this is premised on the notion that “a certain bluntness is necessary to arrive at the truth (which is the sole standard and may disregard other standards of sociability)”. German academics, he adds, tend to avoid blogging and tweeting because “their direct style would be misunderstood in the socially indeterminate space of the internet”.
There is the related issue of humour: a distinct asset in Anglo-American academic debate, it is often seen as a handicap in German contexts, apparently as a result of a widespread opinion that being funny and being serious are mutually exclusive.
But that's an issue for another lunchtime.