To be fair, I don't think anybody has been trying to guess track boundaries for a decade. It's been well known that the number of sectors per track varies because of constant data density and larger surface area at the outer rim of the disc.
Because somebody has to do the write equalization on today's flash, I in fact prefer it to be hardware because there's less chance that changes in software get to break it. If it's all software, you presumably have some kind of data partition exposed over especially rewrite-durable media that tracks the info about flash block write cycles per erase cell, and which must never be overwritten during disk formats for instance. (If not, then I guess you use the same flash chips for wear-leveling information as the filesystem itself, which sounds like another kind of headache. Not sure how these things work.)
It's interesting that modern android phones appear to be using ext4 over hardware remapping layers too. I guess NAND-level chip access sounds better in theory than in practice.