Your PC runs firmware written by some companies with really sloppy engineering and security practices. Whenever possible opt for a computer that runs open source firmware (coreboot).
Windows vendors make extra money by putting spyware on your machine. That's a big chunk of why a Dell machine is cheaper than a machine from a trustworthy Linux vendor: they have a secondary revenue stream that is adversarial to you as a person.
The article you're linking to starts with security researchers who installed their own backdoor which went undetected.
Then it continues with a warning about the dangers of not being able to check if the firmware actually is a firmware actually from the vendor and not a manipulated one.
While I'm pro open source and agree that there are dangers not knowing what firmware is used I fail to see how an open source firmware / bios world be immune to be switched out.