The RTK/RTH method is nothing like learning an alphabet: at no point in my education did we sit down for weeks and "learn the meaning" of A, B, C...etc. For phonetic alphabets like hiragana and katakana and roman and hangul, it's absolutely worthwhile to memorize the shapes of the characters, because there's a small set of them, and once you know them, you can convert written words to sounds. With RTK, that's not true at all.
An adult of average intelligence can learn to read kana in a week. That's time well-spent. Spending months memorizing the "meanings" of kanji is a whole other process, of dubious value.
"Learning kanji and vocabulary at the same time isn't a big deal."
This is true, and is the way that Japanese children learn the language: you learn a character, along with some words that contain the character. To the extent that individual kanji have meanings, you learn them in context.
"I don't know why you are saying "move on" because as I said, it is one more thing you have in your toolbox."
Most people who do RTK don't do it this way -- they do things like the OP, and try to "memorize X kanji in Y days". I think that's largely a waste of time.
After RTK, I created ways to mentally breakdown and identify the characters. Then, suddenly, I was able to learn words much faster too - instead of struggling with “well this one has this curve here and then it points there and it means that”, reading became automatic, and I could focus on the word itself.
I'm intermediate in Japanese (conversational + able to read at an N2 level, albeit slowly), and my first response to anyone who says they "learned X kanji" is "how many words do you know?"
There's probably some value to learning the meaning of individual kanji in isolation, but it's very limited (especially in Japanese). Most words have only tenuous relation to the meanings of their individual kanji, and "learning kanji" is kind of a crutch for beginners to pretend that they're making rapid progress.
I suppose from that perspective, "learning X kanji in Y days" is a useful meme, because it pushes people to quickly move on from the approach. But that said, for most learners, it's much better to simply start learning words.