https://wccftech.com/tsmcs-3d-tech-supply-manufacturing-woes-may-cause-limited-amd-ryzen-7-5800x3d-availability-could-also-explain-no-3d-variants-of-5900x-5950x/

While AMD has its reason for launching the Ryzen 7 5800X3D as the only 3D V-Cache option for mainstream 8 core gamers, it looks like the real reason for having the brand new tech exclusive to just one processor might have to do with TSMC's 3D tech supply and manufacturing capabilities.

Now you must be asking why it is so hard to manufacturer a Ryzen 7 5800X, a 7nm chip with 3D V-Cache? Well manufacturing a 7nm chip isn't hard now as TSMC has years of expertise & their 7nm node has some really high yields. The main issue here is the addition of 3D V-Cache that makes use of TSMC's brand new 3D SoIC technology.