Firewalls and stuff
Actually a hardware firewall built into your router will help as long as the devices aren't available on a wireless network. But then wireless networks can be secured using other methods.
IF the users of these devices went to a real computer store instead of PC World or Best Buy, then the odds are about 50/50 that the seller would show the user how to secure his or her device. Occasionally even those corporates have ethical employees, but those sorts of employees don't last long because corporate electronics stores want to charge for basic configuration, not give it away for free.
Anyway the point of the article is not that stuff on the internet is vulnerable because 100% security is impossible, but rather if you spend 5 minutes learning how to configure the device you can make yourself safe from drive-by hacks.
The following Google search.. okay I won't but there is a simple one that will reveal 1000s of unsecured devices for everyone to take a look at. Even more if you're aware of the standard admin username and password, admin. Or 12345.
So the problem is lazy, greedy or unscrupulous computer dealers don't tell non-techs how to secure their devices in a way that won't make their co-existing PC 100% secure, but will make it safe enough to withstand those who can't be bothered to waste time figuring something out when there's 1000s of other targets out there that don't require any thought whatsoever to access.
And that is actually pretty damn safe. It's like the old joke about the two guys that stumble across a lion. One starts to run and the other asks puzzled, 'do you really think we can outrun the lion?'. The guy that started running answers 'no, but I know I can outrun you.'
Any non-techie that reaches the goal of outrunning the millions of slow people with no security has pretty much made their system as safe as it needs to be, unless he has a disgruntled spouse with the phone number of a good detective agency and a penchant for deleting his WoW toons (I know a guy this happened to and while I also know I shouldn't laugh..).
To anyone thinking, well if they just read the manual.. yeah.. right.. You'd think that at least one manufacturer.. just one.. would employ someone with the ability to put all the required words in a sentence to make that sentence mean something in the language it was written..