I often use tho and other abbreviations as a way to show tone and personality in text. So like, if I’m being very casual and lighthearted I’m more likely to use tho, but if it’s a more serious conversation or I’m typing out proper thoughts then it’ll probably be though. For me it’s similar to how if you put a period at the end of your text then it’s kinda passive aggressive, but using periods just in the rest of the text as normal punctuation is fine