the reason most of us carve blades is because we can make them exactly the length we want. we can also pick the design tsr to hopefully match the load. we can adjust the hub to run 2, 3, 4, or even 10 blades if the needs is there. some PMA's might be best off with a 5 blade tsr 4.5, while others may run best with a two blade tsr7.
the reason we don't seem to be a fan of those skinny tipped, wide big angle rooted hornet type blades is they are typically very noisy and have very little torque. not to mention that that wide, angled root will actually be pushing wind, not being pushed by wind; once the blades have gotten into the higher rpm range. sure this wide angled root helps with start up in low winds, but who cares, your not producing power at these rpms, and just putting excess wear on the bearings.
if the wind is strong enough to produce power, then homebrew type blades will be spinning. who cares if a set of blades start spinning at 3mph? it doesn't accomplish a thing.
then there's all sorts of other blades mass produced out of fiberglass, or even plastic. they rarely have any worthwhile design put into them, and many times have big balancing issues, and durability issues.
then there's the youtube videos of the blades "that really rip!" who knows if the genny is even connected, or just freewheeling. zero rpm measurement, zero tsr info, zero amps per wind speed, heck not even wind speed. but "they sure do rip!"
does this help to clarify the reasons?
adam
