Cartridge Loading and Compliance Laws

After reading into various threads concerning cartridge/arm compatibility, then gathering information from various cartridge manufacturers I am left feeling confused with head spinning a bit.... Ok, cart compliance I get, arm and total mass I get, arm/cart compatibility and the whole 8-12 Hz ideal res. freq. range I get. But why on earth then do some phono cartridge mfgs claim their carts are ok to use with med. mass common modern arms when they are in the highish 20-35cu compliance range? Am I missing something??

Ie. Soundsmith, VanDenHul, Ortofon and who knows, maybe more??

From what I gather, below 8Hz is bad and above 12Hz is bad. If one is less ideal than the other, which is worse I wonder, too low res. freq. or too high?