The only numbers I will ever spell are one and zero, and only when using them as a pronoun, or for emphasis, respectively.
Is there ever a reason to not to use symbols when dealing with numbers? Why would "fourteen whatevers" ever be preferable to "14 whatevers". It's just so much easier to read numbers as symbols, not spelled out.
(Caveat, not including multipliers, like "273 billion").
Not only did you write those numbers wrong but none of them are less than 10. Maybe the readers perceived ambiguity has less to do with their standard conventions than you think.
You're in an engineering community, is ten-one actually wrong?
Consider the sequence: One, eleven, twenty-one, thirty-one, fourty-one, fifty-one... One hundred and one.
As far as the convention of writing numbers out in words when they're less than 10, there's also conventions for less than 15, wikimedia uses the convention if it can be written in two words it's optional to write it out as words.
You're right but in the specific context the meme addresses I would still argue against you. Perhaps in this hypothetical the reasoning for the convention was irrelevant to whether 11 can be written as eleven or ten-one. Ultimately it doesn't matter, we are in an engineering community, on a post about numbers less than ten and you're arguing with me about ten-one being more situationally valid than eleven when we both agree that 11 is just better.
Just a small note on this, style guides have all sorts of weird rules about spelling out numbers, most of which I personally think are nonsense, hence making a meme. Not necessarily just less than 10