Because they are masters of lock-in. I just tried out every single open source or adobe-reader alternative for my wife to read university issued material in PD

Because they are masters of lock-in. I just tried out every single open source or adobe-reader alternative for my wife to read university issued material in PDF. the only one that could render the documents correctly was adobe reader. So, that's what she is using, with all the vulnerabilities. every hour adobe acrobat will add some garbage or do something different with the files it output, that you can only read them in adobe reader. Only printers should have to read PDFs. if even...