That, or if they're like me, the person is just very tired. If I am extremely tired, I basically just hit shift on every word and don't care about it. In such cases, I might fix my posts and comments in the morning, or even delete them if they feel too much like "what the fuck did I write there".
Another key to identify those is double words.
Example: I Only Started Started Using Computers When When I Was 14.
It might come from languages like German where nouns are capitalized. Even in English proper nouns are capitalized so I don't see why that bothers you so much