I looked through those articles, and they’re all about how Japanese isn’t that hard, and it goes over the mechanics of it. But it’s not the mechanics that make it hard (esp. if you drop reading/writing), it’s the sheer foreignness of it.

Pretty much everything about it is different:

• no articles, and it has particles
• order of everything is different (post-position everywhere)
• even simple things like plurals are way different
• honorifics are embedded in culture, not just grammar

And so on. The foreignness and context is what makes it hard. That’s why I’d put it above German in difficulty, even though German is probably more difficult in an absolute sense due to the complexity of its rules.