Earlier quoted context omitted.
Plain text is simple, elegant and has open-standards - it traces its origins back to telegraph codes that we have been using for hundreds of years - and still forms the basis of most of the internet now. So I am inclined to agree with the statement "text is the most powerful, useful, effective communication technology ever, period".
Please elaborate how text is most powerful (in which aspect anyway? define powerful) and most effective (surely it isn't or text wouldn't be the prime example for stuff that's good to compress).
I am not the source of the original statement, but my own interpretation of "powerful" aligns with simplicity and flexibility. Plain text has only slightly more structure than a stream of bytes, meaning it retains a lot of simplicity and flexibility. Yes plain text can be inefficient and is overused (a proprietary unpublished wire-format does not need to use JSON). However, 50 years from now, the only data I feel comfortable knowing I'll be able to read is plain text (and possibly also JPEG and a few other well-specified and simple binary formats).
Many binary formats are effectively defined by large complex and transient code bases that target particular tool chains and APIs. A new binary format needs to justify itself, less so plain text.