Yes.
> even before having to add extra application logic to handle this method being fallible (e.g: if you want to use it to store filenames, you now need a check and pop-up about some OS-valid filenames not being supported).
I don't see why you'd need that. CSV does not have anything like that.
That's a higher-level concern. This ascii-delimited format (like CSV) is supposed to be a stupid row/column format. And also simpler to implement than CSV.
If you're using a fallible CSV dialect, your application does need to handle that case in some way (or in some cases it may be fine just to let it crash). Something like length-before-text is convenient because you don't have to worry about that case.