No it’s not. If Rashi meant what you think then eyes would also be not tznius to reveal, because the same pasuk says ????? ?????. The Gemara is not trying to say that something inherently causes ????. The pesukim are asmachtas.
But now we are touching on the debate of whether there is anything inherently “ervah,” where I didn’t want to go. Suffice it to say that not all poskim are as sure as you that the Gemara means to say such a thing. For example there is the opinion of the Aruch Hashulchan that berachos may be recited in the presence of a married woman’s uncovered hair even though she is obligated to cover her hair; his reasoning is that while she is certainly still obligated to cover her hair, but since it is normal for people to see the hair of married women it has effectively lost its status of ervah.