There's no such thing as a zero-marginal-cost free tier

If you’re a conventional SaaS, by offering a free tier you are allocating money (in the form of ops load, compute, and various other things) in order to acquire customers. Whether or not that offering is correct is not subjective or qualitative: it’s just like any other avenue of paid acquisition, where you look at CAC and you look at LTV and you look at your runway and you call the shot.