Fauci did a terrible job.
He was complicit with the Trump Admin.
Feb 29, just as the disease was getting a foothold in the US, Fauci said on national Tv that no one needed to change their daily activity. Wrong.
Fauci was also a mask denier. Wrong again, Dr. F.
Advocated and promoted the rather fictitious and fruitless 6' spacing guidelines. So Americans got caught up in an arbitrary standard which is hard to maintain and not greatly effective, and not based on any real science. Sure keeping a distance from other people (who may be infected) is beneficial, but the 6' dictum just gave a false sense of security (and was especially harmful when combined with telling people masks were useless and maybe even harmful).
Fauci also played a similar role during the AIDS crisis under the hostile Reagan Admin. And that gets to another issue, Fauci is older than Biden and will turn 80 by the end of the year. You can't find someone who is younger, more energetic, more up on the latest medical developments? Hard to believe. Fauci made a lot of mistakes, provided cover while the Trump Admin went in for stealth herd immunity, and is tainted. Removing Fauci, either quietly or with a boot in his backside, would also signal a clean break from the terrible Trump response. And Birx was worse. Also reportedly a terrible administrator who nobody likes working under.