I tend to agree with Majestic on this. Whereas there may be more examples of explicitly gendered language in Japanese, the idea that women are discouraged from asserting themselves or expressing their opinions is almost certainly more cultural than it is linguistic.
Even in English-speaking countries, there have been countless studies showing how women are perceived negatively for being assertive in the workplace (they might be seen as "bossy", where a man in a similar position is seen as "take-charge").
This would suggest to me that these issues run far deeper than the language itself.
I have some issues with the language analysis provided in the OP article as well. The feminine sentence-final
wa is growing increasingly rare, and nobody would bat an eyelash if a woman said
ii yo instead of
ii wa yo (in fact, the latter might even sound like a slightly old-fashioned affectation). As far as first-person pronouns go,
watashi is the default for both men and women in formal speech. Being deferential and self-deprecating ("I'm afraid I'm not so good with numbers...") is something that both men and women would be expected to do in certain situations (e.g. when talking to a client or superior) and shouldn't be in others. If a female boss is expected to defer to her male subordinate rather than pointing out that he made a mistake, that's an office culture problem, not a language issue.
Lothor said:
Even as a male, I found trying to speak polite Japanese in the office such a straitjacket that I gave up and ended up speaking English to more senior colleagues if their English was up to it despite having reasonable fluency in Japanese.
With all due respect, I'd argue this is primarily a perception/attitude issue, or simply a case of you feeling more comfortable asserting yourself in your native language rather than a second language. I'm not saying Japanese and English are entirely equivalent, of course, but I think it's going a bit far to suggest that the mere presence of
keigo prevents one from firmly stating your opinions.
(I realize that there are even many native Japanese speakers who say they feel more "comfortable" being assertive in English, but again, I think this is almost entirely perception and attitude. They have it in their mindset that there's no such thing as polite language in English and that English speakers are more "direct", so they are able to mentally free themselves from all the cultural baggage that exists in their native language/culture and just speak bluntly.)