Especially when paired with phrases like "who dat". You're just coming across as doing the barely minimum effort to write. Like people that mumble because they can't be bothered with communicating to you.
I'd argue that on a keyboard, it is also showing intention and effort. Everyone is so used to proper capitalization, it comes automatically. I don't have to make an effort to press shift when I press 'I', it's entirely subconscious.
Capitalization is largely unrelated to effort or lazyness. Except for a few extreme cases whose lack of effort is just as visible in the rest of the prose, or the quality of the ideas.
Furthermore, I'd encourage one to spend more effort evaluating the substance of what someone has to say, rather than dismissing their intelligence on account of cultural or stylistic differences. Limiting yourself to a smaller bubble out of disdain seems like self-inflicted imprisonment.