I think the problem is that not knowing one grammar doesn't affect your learning another grammar. But not knowing kanji REALLY slows down your progress at some point because all the advanced materials are written in Japanese using a lot of kanji. When I first purchased my copy of どんな時どう使う日本語表現文型５００ when I only know about 800–1000 kanji, it took forever to read a single lesson. Once understood, the grammar was very, very easy to internalize. But the lack of kanji knowledge was debilitating.

It's like how learning to run is easier than learning to play tennis, but if you can't run, you'll never be good at tennis. If you're 15 and have never run before, it's going to seem a lot harder than playing tennis for a very long time because the "playing tennis" you're learning is confined to "this is the proper mechanics for a forehand," "this is the proper grip for a forehand," etc.

Once dropped into a tennis match with a 5.0+ USTA-rated player, you'll quickly realize your inability to run down the ball does you in a lot more than your mistaken use of western grip instead of eastern grip to hit a low passing shot when your opponent is at the net.

Just my opinion as someone for whom grammar has come a lot easier than kanji.

Actually I find grammar bug me more than Kanji do. Studying Kanji takes a lot of time, but I can usually find the answers in dictionaries, while grammar has many things I can't find out just by searching, and misunderstanding one grammar point can lead to serious mistakes when I read something. For me, difficult sentences aren't about having a lot of Kanji I haven't learned, but with complex structures that can blow my mind off.

I learned Chinese while growing up.

I never remembered learning particles. We just memorized the words.

And we saw the words so many freaking times it just imprinted into our brain.

This is the same for me as well. If you see a sentence you can just look up the kanji, but it isn't so easy when you are trying to look up the strange grammar surrounding the kanji. Especially when you see something that looks familiar, but is being used differently than you are used to without you even realizing it.

1. I assume by "Chinese particles" you mean 虛字.

2. I think this is similar to how native English speakers are not taught words like "at," "on," "through," "by," etc. We just pick them up. But ESL students have to learn them through painstaking work (I know it was tough for me to get used to 虛字 like 的 and others). English prepositions are the evillest part of English, from what I've heard from ESL students.

In the house = physical presence in the building
Inside the house = same
At the house = same, but could also mean you are geographically located on the property of the house, even outside the building itself; also could be slightly more casual than "in the house," possibly implying the addressee has some familiarity with the house in question (i.e., I cannot imagine saying "I am at the house" to my boss, but I would say "I am at the house" to my wife).

I am in Hawaii. = I am located in Hawaii.
I am at Hawaii. = grammatically incorrect
I am on Hawaii. = my feet on located on Hawaiian lands, but practically borders on wrong grammar

I am in the Hawaiian islands. = now, it sounds weird, like you have dug a hole into the islands and sat down there
I am at the Hawaiian islands. = sounds OK, I guess
I am on the Hawaiian islands. = now, it sounds correct

I know of no rule that explains why the correctness of "in" and "on" switches places when I changed "Hawaii" to "the Hawaiian islands." Imagine having to learn this as an ESL student!


Or maybe the use of articles in English is the worst. Consider this (and pardon my French) important distinction:

He is shit. = He is not good.
He is the shit. = He is very good.

You are man. = You are a member of Homo sapiens.
You are the man. = You are successful and respectable.