If you look worldwide Intel still sells more systems overall. The issue is even in many DIY markets such as Asia,etc AMD is less available and not even many times price competitive. Just look at the Lowspecgamers channel and he points out such well known value CPUs such as the Ryzen 5 1600AF were not available in the markets which needed them most or not even price competitive. AMD mostly seems to target some parts of Western Europe and the US,but it gives a distorted view of actual product availability. So if you think the shortages of Ryzen 9 CPUs are bad here,then think how bad it is in many other parts of the world.
Then there is the bigger problem - most buyers of PCs don't care about keeping upto date. For them an AMD or Intel CPU does not mean much as they have no clue. Even if they read one is "better" than other,if they go to buy a laptop or desktop,then its what ever is available at the time.
It gets even worse with laptops - the availability of Zen3 based Ryzen 5000 series APUs is dire,and many of the decent laptop ranges don't have even Ryzen 4000 options,and even then they seemed to be specced worse than the Intel equivalents. Even when I tried to look for laptops for my mate,the ones which fitted their requirements seemed to be mostly using Intel CPUs. Despite me saying its a shame they don't have a Ryzen 4000 CPU,their attitude summed it up for most,mostly along the lines their laptop was so old,ANYTHING would be an upgrade,which is kind of true.
Also the Core i9 models are the ones which arguably are very overpriced even compared to the overpriced Ryzen 7 5800X so its not surprising. But the issue is I think you are ignoring the fact the CML Core i5,Core i7 and Core i9 CPUs are now also cheaper. The fact is even when Zen3 launched,Zen2 and Zen+ simply were selling more units.
The thing is also AMD "selling out" and Intel "not selling out" does not mean much if AMD has very much less stock and Intel has 10X the stock. It only really indicates AMD is severely understocked and that can be seen with the 12NM APUs being nowhere to be found.
This is starting to cause problems for AMD,as they are loosing marketshare worldwide in 2021.
Even with substrate shortages potentially Intel has enough financial clout to push the issue,whereas AMD does not. This is a bigger problem during the next year or so and I am somewhat concerned for AMD. This is one of the problems of not having your own fabs - yes you can be more agile and shift to newer nodes without the financial burden. OTH,it also means you are at the mercy of every other competitor who wants that capacity.
How is a budget APU going to work out on 7NM? AMD is selling CPUs with 70MM2 to 80MM2 chiplets,and can't get enough supply. You can't even get a full yielding Zen2 chiplet based CPU for under £240~£250 because AMD wants its higher margins now they are in the big leagues. The APUs are 150MM2 of 7NM silicon at least IIRC. Yields are going to be worse and you get less chips per wafer. Its quite clear AMD doesn't care anymore for its DIY buyers and gamers,as it will gladly eat margins supplying larger 7NM APUs to MS,Sony and OEMs. What we are getting is basically overpriced dregs!
The sad thing is until AMD actually has a Zen3 SKU for £150~£200 with similar core count to whatever Intel has,I have stopped recommending any of the AMD mainstream CPUs in most cases now. The Zen2 CPUs are slower in gaming,worse in PS,worse in audio benchmarks,etc. Even the platform upgrade is pointless as I know many who never change out CPUs,and even if they were, if you are looking at a sub £200 CPU,I am uncertain whether many I know would suddenly spend £300~£400 on a CPU,when its better spent on the GPU.The people who want £300~£400 CPUs in my experience tend to buy them upfront.
AFAIK there is no real reason for that BIOS block,but AMD did the same with PCI-E 4.0 with the 400 series motherboards,when the rebadged B450 OEM motherboards,ie,B550A were fine. The Ryzen 5 3600 isn't worth it especially for a entry level/mainstream gaming PC. When it launched it had 2X the threads of the Intel competition and was cheaper,but lost in gaming,latency dependent and lightly threaded benchmarks. Intel CPUs needed Z series motherboards to tweak RAM. Now the market has changed and AMD offers no single threaded advantage,no thread count advantage,no PCI-E 4.0 advantage,and no RAM tweaking or overclocking advantage anymore on cheaper motherboards.
Even having an IGP actually helps Intel especially since GPU shortages mean many people are using older and older GPUs. At least the Intel system will sort of functional GPU if it goes,but with the AMD system it does become an issue.
Even power consumption isn't a slam dunk especially for mainstream CML. For example I was surprised to look at the power consumption of the Core i5 10400(The Core i5 11400 is more but Zen+ levels AFAIK). The Gamersnexus review had it similar to a Ryzen 5 3600. I can confirm this with my example - even when it's set to short term TDP boost of 80W,but sustained at 65W,with a Alpenfohn Black Ridge low profile cooler,in a 5L mini-ITX Velka 5 case it seems mostly fine.
My Ryzen 7 3700X can be beaten by a Core i5 11400 in a number of games,and so can a tweaked Core i5 10400. The issue is that many games are still optimised for Intel CPUs,and the latency penalties due to the dual CCX design still reduces performance overall in games,audio stuff,etc.