Tbh it’s probably less of an Adobe problem and more due to the absolute mess that is PDF annotations.
Despite being a defined open standard, most free PDF viewers either don’t support them (zathura etc), or fuck them up (GNOME evince). Even some of the viewers that do support them like Okular need extra configuration.
Unironically Firefox as a PDF viewer actually has the best support for PDF annotations.
The state of PDF Readers on Linux - Discussion - It’s FOSS Community - https://itsfoss.community/t/the-state-of-pdf-readers-on-linux/12798
Even browsing existing small to medium sized sites has become such a chore, with all these verifications and rate limiters as part of the anti AI scraper effort.
So many cloudflare verification checkboxes. So many Google sign ins. So many cross site cookies and tracking for even basic functionality.
Care about privacy and restrict browsing data even a little? Captcha hell.