The reasons behind vendors ignoring this are simple.
1. Margin - ZZP makes a majority of its money based on the fact that most of the stuff they sell is on a 300% markup... A TVS blower they pay $1750 for and sell for $1800 is not worth the 20 phonecalls they will recieve before selling one.
2. TVS install kit - They need to make and sell an adapter plate kit... this will run about $300 with the throttle body adapter, and whatever you need to adapt the stupid crap you have to move around in the process. Now you need an 8 rib kit, modular pulley system, cam, springs, timing chain, maf sensor, intake kit,
3. Turbo kit - ZZP makes its money with turbo stuff... they make the parts (almost unlimited margin here), they make good margin on the turbos (as they are nearly 1/3 the upfront cost, the markup is easier to stomach). ZZP also is able to charge for "R and D" at this point, and sane people would actually pay it.
4. relitive gains - You just spent $5k+ (retail) on a TVS kit and cam setup... You go to your local grand prix meet up and race some other people.... and some guy with a gen5/xpz walks you like you are standing still and left wondering why you didnt spend HALF on a z7 kit and made 400whp on 93 octane.