You can find excellent examples of english written before capital letters (or even spaces) were standard and they tend to be significantly harder to parse because we're not used to parsing them. Familiarity is part of the problem but I also think that more visual clues allows for faster parsing and comprehension overall.

Different languages and cultures. When you spend a lifetime building reading clues, throwing them out the window makes it harder for people. The languages you mention also have delineation methods that involve more than simple punctuation marks.