Isn't "BIOS reset password" a security flaw?

According to this article Dell Support can help a user to gain access to data after forgetting the HDD password:

Once Dell Support has provided the reset password, you enter this when prompted and then press Ctrl + Enter to complete the process.

... the BIOS should accept the reset password, clear the password, and allow access to the hard drive.

Isn't this a security flaw? Shouldn't only someone who knows the HDD password have access to data?

Does other PC / BIOS / motherboard manufacturers provide similar means?

What is a good resource for understanding how hardware based disk encryption (FDE?) works and how the procedure described above is possible?

(The message was posted also here.)