Why cartridge compliance and resonance matter
The turntable tonearm and phono cartridge resonate at subsonic frequency that depends on the effective weight of the entire tonearm (including headshell), cartridge and mounting hardware as well as the compliance of the cartridge.
The resonance is usually below the audible range, but it may still cause problems with footfalls or record warp when it’s too low or have effects in the audible range when it’s too high.
This calculator will tell you the resonance frequency of your system and whether it is too low or too high.