I have told you.Why would they sell the cutdown N33 for the same price as N23 or <$300 when they can sell It for more?
Why would they make a 6GB part instead of 8GB?
With N23 we already saw the amount of faulty chips were negligible, If that wasn't true then they would have released such version for OEMs at least, but they didn't.
You will reduce cost by using only 3 chips instead of 4, but you also need chips with higher speed to compensate for the missing bandwidth, and they cost more.
You can have the same bandwidth by using 6GB Vram at 24gbps or 8GB Vram at 18gbps. So is there a noticeable difference in BOM between them? Buyers would certainly prefer more Vram.
1) you sell it for around $300 because lots of 2nd hand mining cards are going to be on the market and the financial situation is very different so I am not sure an entry level 7500XT could sell for much more than $300.
2) You make it 6GB because that reduces the memory cost by 25% and you reduce other parts of the BOM as well like cooling, power delivery etc. It also serves as a point of differentiation so that you don't harm 7600XT sales.