Dear @dogberry : TRansducers always are the more important links in the audio system because with out transducers we can't listen MUSIC.
Now and taking in count that today almost no one owns only one cartridge then I think that the primary system link in alogue is the Phono Stage because is this unit the one that perhaps has the hardest work with the audio cartridge signal due that needs amplify that tiny lvelsignal over 10k times and needs to do it with very low noise and with very low developed distortions along to has a " perfect " inverse RIAA eq. that's an equalization f around 40dbs ! ! . The unit needs too all the facilities to handled any LOMC or MM/MI cartridges: it has to be universal and most be an active high gain unit with no SUT ( no pun intented. ). The Phono Stage main target most be to preserve the extremely sensible and tyny level cartridge recorded signal and I mean it: Preserve its quality. Extreme hard task for say the least.
Following with the same way of thinking the second link is the tonearm that has to be one that " accepts " cartridges with different compliance/weigth and stays inside the ideal resonance frequency.
After those links comes the cartridge where " ironically " the other two links operate as cartridge slaves.
Yes, TT is way important too but according with my way of thinking is not more important, critical yes but today TTs are really good.
Regards and enjoy the MUSIC NOT DISTORTIONS,
R.