Earlier quoted context omitted.
FSAs are insane, conceptually. "Guess how much money you're spending in a year on healthcare! But beee caaareful: if you guess too high, YOU LOSE IT" I still used mine while I still had access to one, but it was grumpy-making and was usually almost more trouble than it was worth.
It is a relatively easy fix tbh. You spend on medical bills through the account like you do right now, but the way you fund it is your post tax contributions. At the end of the year the account sends you a statement of what you used and you can use it to get the tax paid on the money back when you file the taxes.
If you underestimate the amount you spend by more than the rollover limit, you can't get that money back.
So on top of the broken employer-tied health insurance system, we have gamified the financing of out of pocket medical expenses.
On top of that, if you lose your job part way through the year, you lose the balance of any FSA funds remaining (they belong to your employer - I found that out the hard way).