Why aren't popular book trackers offline-first?

It was 9 am on the train out of London St. Pancras and I had just finished the last chapter of a book I had been reading for weeks and I tried to log it on that rain forest app (you know which one :D) & it just kept spinning due to no signal and then the Software Engineer in me thought - I just want to note that I finished a book, why does it even need the internet?

Then I started building Pick Up during that weekend and designed it with an offline first architecture and then I realised I needed more than a log. I also wanted to capture how pages in a book made me feel - in my voice and also transcribe them into texts.

As someone obsessed with details and clean UI, I went to extra mile of keeping it simple and intuitive. I care about how apps feel in my hands - every interaction has to earn its place and its interface needs to feel polished with nothing getting in my way, so I ensured Pick Up was designed and built with the aforementioned philosophy.

If you’d like to see what makes Pick Up more than just a book tracker app, feel free to have a look at its features: https://pickupreader.com

I also wrote up a post on how Pick Up compares to other book trackers like Goodreads, Storygraph, Bookmory etc: https://www.pickupreader.com/blog/reading-tracker-comparison

Perhaps there are technical or product reasons I'm overlooking, but after building Pick Up I still think readers should be able to track their reading whether they're online or not.

I'd be interested to hear what others think.