Because human beings don't have infinite time on their hands, I expect. Despite the seeming behavior of the posters here (especially myself) to the contrary.
I would say that rather than poking at people on some random message board about a topic with no connection to the forum topic, you might want to check out
Deitel's own resource page about Ruby and contact them yourself.
Seriously, I didn't even know there was one¹, and I found that as the first result in
a DuckDuckGo search on "Deitel Ruby".
There are also plenty of fora where Ruby
is discussed regularly, starting with
the official one. While it is technically on-topic in the General Programming board here, and I am sure that there are several Rubyists here, it hasn't come up that often here. This is simply the wrong place to ask about it.
Seriously, if you aren't looking to talk about developing operating systems, leave. Not for our sake, but for your own, because we are not the people to ask these things - we probably don't know the answers. While the General Programming board isn't about that as such, it is only really here as a service to members
who are already talking about OS dev in the forum but who wanted to discuss off-topic matters.
You are doing yourself a disservice by asking these kinds of questions here.²
I haven't looked at Ruby enough to have a solid opinion on it, what I've seen of it is looks pretty good for a language in its use space but I just don't have enough time in with it to say. I did have two projects related to it, but neither got very far.
The first was using a RoR-based e-commerce system called
Spree³, which ended because there were problems with the existing webhost⁴ and I couldn't find another affordable host who supported it.⁵
The second only got as far as a proposal which I had given someone which was rejected as too as too high and too long (I still stand by our estimate, what he wanted was going to cost that much no matter who he took it to, if anything I'd low-balled it). Oddly, my limited experience with Ruby on Rails wasn't a factor in the rejection AFAICT, since that was just a projected option rather than a specific technology recommendation, though I was hoping for it to be chosen as it seemed to be a good fit.
Footnotes
1. It wouldn't have occurred to me to look, because, frankly, Paul and Harvey Deitel never impressed me. At all. I know their books are popular and widely used, but the texts always seemed very overrated to me - not terrible, but not all that good, either. But then, I haven't looked at any of the ones after 2003 or so, I think the only one I really trying to read was the fourth edition of Java, How to Program, and if memory serves, I found it so dull and poorly written - not to mention frequently inaccurate in the intro chapter, which is almost Herb Schildt level incompetence - that I couldn't get through the first chapter.
2. And if you are a paid provocateur trying to troll the board, as has been suggested about some others in some of your threads, you can FOAD. I can't imagine that being done here of all places, though, because seriously, why would anyone bother? That would be a serious waste of manpower that could be put to use on, say, posting even stupider questions on Quora or Sewage Overflow, or posting hateful screeds about politics on image boards devoted to adorable kittens - places where there are enough people reading it to matter. This forum? Probably fewer than 100 visitors a day, not counting the web spiders and other bots. Trolling us is pointless.
3. Which was for my father, actually, on a project I was begrudgingly involved in for a promise of repayment later. I came to regret this, as you can imagine. I did expect that I would, actually - my real mistake was that I did it anyway.
4. Tip: don't go three months without paying for a project-critical service and then not tell the webmaster - who is living in your own house - that your web hosting is about to get yanked. Dad did that sort of BS. A lot. And then crowed about how clever he was for having put one over on them by not paying them 
, while the bills kept mounting. I regret everything about the six years I spent 'assisting' him after I left California, I really do, but at the time (March 2009) I was in deep financial trouble and didn't really have any other workable options.
5. Spree was a relatively immature package which had a lot of teething problems anyway, so it wasn't really a loss; the worst part of it was that the replacement was Magento, which meant dealing with PHP... and, well, Magento.