I tried "this dish contains rice" and Duo whacked my knuckles again.
You are correct, Archie25. "Alright" is still widely considered improper (it originated as a misspelling of the phrase "all right"). In written word, I've mostly seen "alright" used in dialogue. This is usually to add style. There is, however, a difference in the meaning of "alright" and "all right" that must be noted. "Alright" (if it were a formalized word) would exclusively mean "satisfactory/acceptable/okay." Whereas "all right" may mean "satisfactory/acceptable/okay" or "all correct/right in every aspect" depending on the context. Because of this, the misspelling offers disambiguation potential. Consider, for example, the difference between these two sentences:
"The figures were all right," and, "The figures were alright."
or how about,
"Today I saw a man claim that he could survive a fall from a ten-story building. Then he dove right off!"
To which the response, "Well did he turn out alright?" is thoughtful whereas the response, "Well did he turn out all right?" is darkly hilarious.
See how there is disambiguation in using the apparent misspelling? Because of this, the use of "alright" is becoming more and more accepted over time (somewhat akin to how "their" is slowly becoming more acceptable as a neuter singular possessive).
tldr; It's wrong to use "alright," but it could become all right in the future.
I'd agree with you if there weren't already perfectly good alternatives for the use you propose for "alright". Of course, the average ability to spell could be improved dramatically by accepting the most popular alternative spelling for, say, the 1000 words most commonly miss-spelt.
I mean, there's "altogether" and then there's "all together." There's "already" and then there's "all ready." It's a common English pattern to create clarity by shortening a phrase into a word, and I disagree entirely that this is on par with misspelling "they're" as "their." Rather than creating more confusion by allowing multiple acceptable spellings of a word that has equally distinct meanings, this in fact works in the opposite direction. It doesn't subtract from the clarity that the English spelling system offers for homonyms. Instead, it creates a new distinction between what otherwise might be confused.
Still, different strokes for very different folks.