If you were to start from the beginning would you have opted to buy the newer early 2019 iMac given it is $200 more expensive than your older mid 2017 iMac?
Answer: Yep
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On the product page where you screenshot came from also includes tech spec & price comparison between the three 21.5" iMacs SKUs. Your iMac has 7th gen Intel chips, slower RAM and a non-4K res display. The other 2 iMacs have 8th gen Intel chips, faster RAM and 4K res display. That in itself shows an implicit generational difference.
Answer: (Actually, copy & paste from a post in this thread.)
Yeah, I blew right by that and didn't associate 7th gen with the 2017 Mac. I just figured that's why it's cheaper, but it was still one or the most current iMacs.
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Apple's supply chain is very lean so it is highly unlikely for you to receive stocks manufactured earlier than a few days/weeks prior to your purchase.
Answer: How do you know that. Do you work for Apple?
You disagree with several employees that agree it may be overstock. Do you think Apple would be selling 2017 models online if they had only ten pieces.
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On the product page where you screenshot came from also includes tech spec & price comparison between the three 21.5" iMacs SKUs. Your iMac has 7th gen Intel chips, slower RAM and a non-4K res display. The other 2 iMacs have 8th gen Intel chips, faster RAM and 4K res display. That in itself shows an implicit generational difference.
Answer: (Actually, copy & paste from a post in this thread.)
Even though I am very good at fixing pretty much anything on a Mac that isn't hardware (sometimes, before the Apple rep gives me an answer on the phone) my weak point is the specs when purchasing a new computer (especially when the hard drive is failing on the one in my home).
Lesson learned

Next time I will go to 14th street and pick out my model.
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Finally, If you registered on MacRumors in 2020 I'd get why you'd feel treated unfairly but you've been here since 2008. This forum caters to individuals who generally follow Apple rumors for the latest and greatest. I find it incredible that you were caught off guard by your SKU debuting 3 years ago.
Answer: As stated above, "Yeah, I blew right by that and didn't associate 7th gen with the 2017 Mac. I just figured that's why it's cheaper, but it was still one or the most current iMacs."
I'm happy you know what kind of individuals Apple Rumors cater to.
Are you an administrator on this site?
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I am simply saying that if the iMac was listed as:
2.3GHz dual-Core 7th generation Intel Core i5 processor (2017 model)
...it would be more transparent.
I don't come to any site for the "latest and greatest". I come when I have a question, or an issue, or most often, to help others emphatically.
I can also say with a certain degree of confidence if the Apple store sold this model without telling their customers, they would soon stop because of the amount of returns.