I would not say “It sucks”, but I would say that is not practical. Because it relies on copy-paste, and more importantly, it relies on OSs keeping the exact same form of the charactors copied. In fact you said it yourself, it does not work on mobile. But, 55% of traffic is on mobile.
How are people supposed to share their hidden text? They cannot message it to eachother (Does not work on mobile). They cannot send it via email (It gets converted). General encryption is a lot more versatile. For example, I can send this plain text to my secret correspondent, and since they know how to decode it, it works.
My Version: YldWellXZGw=
Your Version: Hidden Message
Copy and paste your version into your website, i’ll bet it wot work.
EDIT: Can you decode my text easily?
EDIT2: And although your version is very inconspicuous, all I have to do is run it though here View non-printable unicode characters to find out that it is hiding something.