These kind statistics are a kind of lie in themselves. You can say something like "omae wo aishiteimasu", but that's no more a normal way to say "I love you" than "I'm bonkers for that shithead". That has nothing to do with the grammar, it's lexical. "omae wo aishiteimasu" has a different meaning from "anata ga suki da yo".
But also, English has plenty of words for snow, here's 50: https://www.thoughtco.com/snow-terms-types-3010117
That's exactly the point being made - that there are lots of permutations whose individual words mean "I" and "love" and "you", but most of them wouldn't convey what the speaker wants to say, so it can be hard for the learner to choose correctly.
I mean, a set phrase like "I love you" is probably a bad example, since it's more or less idiomatic. But for the general case - a learner wants to say something involving "I" and "you" and a copula - I think the point being made in the article is valid.
But on the whole, no. Just no. I think what's said in the article on this is bullshit. As for wa/ga, one can not necessarily replace the other, so you'd lose a few permutations on that alone. Also, there are more personal pronouns to choose from if that's the game.
I also did not know that just because speech level is grammatically encoded in Japanese, one is not allowed to generate similar meaning in other languages.
Or rather: I'm sure I can find 248,026 ways to say "I love you" in some other language as well.
What is it with Japanese that triggers this kind of ignorance and Sapir-Whorf-ism...?