FSA's are literally just a way to steal from workers. The idea of a use-it-or-lose-it savings account is vile and just serves as an excuse to cut benefits while subsidizing a small group of financial predators.
One of my jobs changed HSA providers like 3 times in 5 years. Had a few years worth of employer contributions get devoured by fees because it was a pain in the ass to get the right forms to transfer the balances.