Well boot sector viruses used to be all the rage in the 90s, they’re entirely impossible under secure boot
Malware rootkits were a pretty big problem about a decade ago, I understand the techniques those mostly used are more or less impossible under secure boot now too
Then we could go into all the government and adjacent industry use cases where state-sponsored targeted attacks are a real concern. Measures like filling USB ports with super glue and desoldering microphones on company laptops is not unheard of in those circles, so blocking unknown bootloaders from executing is an absolute no brainer.
Saying it provides no security is just not true. Your front door isn’t only secure if someone has failed to break in





I’m not recommending it, I’m describing why saying it adds no security is silly.
The keys being compromised on some motherboards doesn’t mean the whole concept is suddenly inert for every single user
If everyone has a copy of my passwords and authenticator keys, that wouldn’t suddenly make 2 factor auth a compromised idea.
Hell, even if you are one of those people running a machine with the compromised keys, it’s still going to block malware that was written before the keys were leaked unless malware authors have also figured out time travel.