People judge you by the way you type just like they judge you by the way you talk. Your typing comes across as immature, as the stereotype is people who type worse tend to be young. It's also kind of annoying to read, just like anyone else typing with many grammatical errors - it looks weird.

It's a perfectly valid response not to care and keep doing whatever you want. But you'll have to accept the consequences of people judging you and mentioning it.