Yes, clarity and grammar matter. For example, with your lack of capitalization, I wouldn't know if you were trying to help your Uncle Jack off a horse or your uncle jack off a horse.
okay, you can also come up with plenty of examples of ambiguous parses that don't require violating any grammar rules. fortunately humans are a bit more intelligent than compilers and can use their knowledge of context to settle on the more reasonable interpretation.
But why make other humans do extra work to parse you? It’s arrogant in the extreme to say ‘that’s good enough you figure it out’.
Even scanning text is jarring when the rules aren’t followed, takes extra time to comprehend and adds to the minor irritants of daily life and will have people judging you, even subconsciously, as unintelligent.
I'm a fan of learning grammar well, to be clear, and wish mine were better, but this is not a good argument for grammar mattering.