Addressing points 1 and 2: I am already keeping a backup of my story. However, it would drive more engagement to the site if everything was already there without the need to go to different places. It would also be an additional distinguishing feature of Scribble Hub compared to other writing websites.
Please explain why you need to go to different places to get your chapters. Are you not saving your story on your computer?
You save your story locally, and you copy and paste the chapters to upload. To upload to multiple platforms, you copy and paste the same text into the text editors of the platforms. I only see this feature as repetitive, not distinguishing, and I don't see how it drives more engagement.
Addressing points 3 and 4: Offline viewing could be a real draw for subscribers, like a juicy Patreon perk. We're not talking about killing engagement here; it's about giving authors more ways to connect with their readers. You do not seem to understand that the offline viewing is strictly a form of freedom for the author, and one that can be used as an incentive for the author to gain more paying subscribers. Actually, let me further explain things I thought I didn’t need to explain. A PDF file would not be hosted on Scribble Hub. Why would it? The website isn’t a filehost. This statement invalidates all the arguments in point 4. How did you come to the conclusion that offline viewing invalidates author-reader engagement? It is a feature for the author side, not the reader side. It is completely up to the author how they wish to utilize the feature. To help you understand, go look in your account settings in the forums. How many of those settings have you personalized? How many have you not? It’s your choice what you do with those settings. Similarly, it is up to the author’s creativity with how they would wish to utilize the feature. I simply suggested they can use it as a paying-subscriber’s Patreon benefits (downloadable chapters which means offline viewing), though maybe I wasn’t as clear as hoped.
In my response, I assumed you wanted the site to combine all story chapters into a single PDF, but you seem to want a different PDF file per chapter. Now I'm more confused about the purpose of this feature. Maybe its a compromise for using lighter resources but the feature is more niche. It also sounds less usable if a book has 500 chapters.
Yes, offline viewing and downloadable chapters is like a Patreon perk, which is why authors do it on Patreon or sell their ePub on another website. Patreon already incorporated a tier system with incrementing benefits for the higher tiers, which authors like to also use to provide advance chapters. It is a service the author provides to the reader. Unless you've set all of your posts to be open, people cannot freely gain those benefits.
Paying subscribers like moving to Patreon to read because they usually can read and comment on advance chapters. On Scribble Hub you increase engagement by increasing your visibility by in novel views, favorites, and readers. Nobody pays to read on Scribble Hub. No, your explanation did not invalidate point 4 and nowhere in Point 4 did I say anything about hosting PDF files on SH. I also didn't say anything about hosting PDF files in Point 3.
I'm saying the feature decreases engagement on this site because readers are downloading the chapter and not actually viewing it. In offline reading, you can't favorite or comment on chapters. Find a spelling mistake? You can't point it out offline and you'll forget after an hour. Comment

? You can't because you're offline.
Addressing point 5: Scribble Hub actually enlists the help of Cloudflare to prevent web scrapers from copying the website. So... if anyone has to steal chapters, they will need to manually copy and paste and format each chapter. You know what a person will have to do to copy PDF files, if offered? Manually copy and paste and format each chapter. There is literally no additional risk. It is the same no matter what.
The point made more sense if you assume the PDF was the entire novel. The site has Cloudflare but SH authors still had their stories scraped, so no comment. My point is about how it's easier to copy text on SH than other sites that block inspection. SH is also not Amazon-affiliated like RR so its harder to pretend to be the author and secretly sell it.
Addressing point 6: It’s a feature request. A request. It isn’t set in stone. It is a suggestion. It is a spark for creativity.
I know it's a feature request. I'm replying why I don't think the feature request will be accepted. I also know a lot of feature requests aren't addressed because SH is only run by a single guy. A lot of people want SH to add a discontinued/potentially abandoned story status, but the guy seems like he already has his hands full so features aren't added easily or quickly.
If you still want to give readers a way to download chapter PDF files, you can attach links to file host sites in your Author notes, and it's something every author can do without asking Tony to add another mechanic. Scribble Hub also has ways to connect your SH account to Patreon, Ko-Fi, etc.