Have any proof of your claims beyond just your one experience? Because having worked as a hardware tech, who primarily did laptops, I can tell you that sounds like the SOP for diagnosing and troubleshooting.
If a customer is having some kind of issue with their laptop, and it could be the battery, AC adapter, or motherboard, you start with the cheapest and easiest component to replace, usually the AC adapter. If that doesn't solve the issue, you move onto the battery. All else fails, then it has to be the motherboard. However, a large percentage of people will have the issue resolved by either the AC adapter or battery being replaced, especially if the laptop is rather old and the battery may be consumed and AC adapter damaged from some chunky volts coming down the line at various times over the months/years. Sounds like you were one of the unlucky few who end up with a bad motherboard.
Also, it sounds like you were trying to troubleshoot this yourself, via the phone support from Dell, instead of taking it to a repair shop where they could have tested it with a known good AC adapter and battery to find out that it was the motherboard. To say that this is a scam would require considerably more proof than you've offered up so far. Based on what you have said so far, Dell would be will within their rights to take you to court for defamation.
Dell runs a scam where a message will appear that says "Computer does not recognize the AC adapter...."
They are trying to get you to buy a new AC Adapter or new Battery.
Then after that does not work they will tell you you need a new Motherboard...which costs about 80% of the price of the original laptop.
This is despicable scam and Michael Dell should be ashamed that his company has running this scam since 2008.
Michael, is the problem is most assuredly not with the adapter, please do not lead people to believe they can fix it by SENDING YOU $80 FOR A NEW DELL AC ADAPTER. Be honest with your customers.
And the customer service...entirely based in India...sucks.