Firmware is the link between software and hardware. Hardware vendors are often very secretive about their technology, and part of that secrecy is carefully guarding their source code. Consequently, firmware usually means blobs, that is, binary large objects. No source code is available.

Unfortunately, closed-source, proprietary firmware contradicts everything Debian stands for. Binaries without the source code are also a problem from the admin's point of view because the hidden code might hide vulnerabilities that the user is not able to fix. Many users don't like the fact that firmware cannot be patched as easily as source code when a security problem occurs. Without the manufacturer, who has to provide the security updates, you can't do anything. And the distributor will want to thoroughly test the new firmware version before it goes to the user, which slows down the process of fixing problems.

In general, proprietary firmware does not score well on the popularity scale with Linux users. However, users are in a quandary. Either you swallow the bitter medicine and live with closed-source packages, or else you do without the hardware and other proprietary components that depend on them. Virtually no one who uses Linux in a professional setting can afford to operate without proprietary firmware. When I used to install Debian, I (and probably many others) directly enabled the contrib (contributed) and unfree packages – initially, out of curiosity or ignorance, and then later knowing that I wouldn't have much fun with the hardware if I installed it without some proprietary drivers.

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