not something to buy so your (grand)parents can use to surf the web and check their email.
The reality is the time to custom build those machines is long gone, today you should just a mini-pc. It won't be as modular (I wish socketed mobile cpu's made a comeback!) but it will be much more efficient and easy to maintain.
The 6400/6500 were tiny, made of spare parts form the mobile lineup, and nobody bought them.
I think the ammount of sales of the 6500 are very underestimated. The price sucked at launch, AMD played the sellers market of the time, but there's absolutely a market for those tiny GPU's, especially now at a more reasonable price of 100$. The recent launch of the Intel B580 shows how the market is starved for reasonably priced gpus, so the does the strategy shift from AMD away from the top end market. AMD was doing much better with the RX580 than it is with the 7900xt