I wasn't referring to any problem. Again, all those PDFs I wrote about are intended for reading only; no filling in, signing or other form of interaction other

I wasn't referring to any problem. Again, all those PDFs I wrote about are intended for reading only; no filling in, signing or other form of interaction other than reading letters that form words on a page is involved in any way, and that is entirely fine and how it should be, so both the PDF itself and a PDF reader that has no form-filling functionality would be entirely fit for purpose (notice the word "reader").