I think it’s a combination of things. I don’t think AMD have given up or that they could ‘easily’ do anything and have decided not to.
Firstly you have to give Nvidia credit, their engineers are obviously incredible at what they do. The 4090 is something like 76 billion transistors? These are some of the most complex consumer products in the world to design and engineer. It’s not a given that a company even like AMD can make a product like the 4090, it takes huge amounts of resources. Nvidia are happy to invest that resource in to a product like the 4090 because firstly they have the capability and secondly because it helps maintain their brand image as the pinnacle GPU company, which also helps them sell cards lower down the stack.
Nvidia’s products are all GPU centric so their business is built around it.
Perhaps AMD could make a true 4090 competitor - but at what cost? Not just to the consumer, but the resource they would have to throw at it to deliver it. As a business they’ve obviously decided that isn’t very feasible for them, they don’t have unlimited resources and these products aren’t easy to design or make. It’s not like GPU engineers grow on trees.
We haven’t had products this competent from AMD for years. I remember quite vividly not that long ago when we got rebrands for ages, like the 280x being a 7970 and subsequent products like the 480 which weren’t capable at the high end. The 7900xtx isn’t perfect, but it’s a pretty solid alternative to a card like a 4080.
I'm not saying AMD doesn't make competent products the issue is they are poorly priced and poorly positioned.
I also don't take issue with AMD not competing in the high end, that's a fair position to take, but they have joined the high end prices whilst not competing. I had a RX480 it was a brilliant card I was one of the lucky few who managed to buy it for £250 at RRP before the mining boom took off then they started going for £400 plus, I actually managed to sell mine for the same price I bought it when I upgraded to a 1080ti 2 years later. The difference was though is that the 480 was positioned perfectly an excellent price with excellent performance for that tier of card.
The current issue is AMD has simply lost their positioning.
I compared this to the Ryzen 1 launch because it was played perfectly, seriously undercut Intel whilst offering a new platform, promising easy upgradeability etc they subsequently lauched the following products still significantly cheaper (albiet creeping up in price) but they controlled where they set the price, AMD dictated the price points, AMD dictated how much a chip should be worth. Intel were charging in excess of £1000 for their flagship... because of that AMD won market share and had the revenue to control the future, now you can buy Intels flagship for under £700 that's 100% thanks to AMD, and now in my circles and personally I do think AMD have the better product. But they have that because the recognised what they had with Ryzen 1, it wasn't a killer but they placed it at such a point that it made the competition seem ridiculous. I think I paid something £300 on launch for the 1700x? now it might only be 80% of what Intel was at the time but when you get get 80% for under half the price it makes the competitor look ridiculous in what they offer which is a good position.
The problem with their graphics division is they have bowed to Nvidia, Nvidia dictates the price points and AMD bows to those prices, Nvidia set such ridiculous prices where you can make the argument that the vast majority think the pricing is stupid, even those who bought the 4090 atest to that, Nvidia said a 4080 is worth £1200 to AMD said ok lets do that, sure you can call it $1000 but the reality is the launch price was well over the MSRP (at least in the UK) and the only reason it's even close $1000 now is because it completely failed to sell when it was the same price as Nvidias 4080s which it was on launch. AMD should learn from their Ryzen 1 approach, seriously aim for market share get that revenue, get that growth, get people so stop talking about driver issues and the negatives thanks to first had experience then that revenue can be used on R&D to become number one, that's exactly what they did with the Ryzen line of CPUs.
With regards to the 4090 point you make, AMD could easily make it, they have said themselves on record but they wanted to keep the price under $1000 and didn't want the power draw considering the comparisons between the 4000 series and 7000 series with power anyway they were way off in performance in that category anyway.
Truth be told i'm really hoping AMD take the Ryzen chip method to GPUs and have multi core GPUs perhaps if they can go that route they will be able to create some absolute monsters at reasonable prices it's actually an area where AMD's experience really outstrips both Intel and Nvidia in every way possible.
Currently however, until AMD makes such chips next generation of cards the really cards i'm looking forward too... and I can't believe i'm actually going to say this... is Intel...