Anything can be "hacked" given enough time and dedication, including webcams and microphones on phones, laptops and desktops. The actual risk depends on your threat model and adversaries going after your data.

I'm very confliced in how to address your question. The source you are quoting is flawed in a number of ways, and really comes across as the observation of an alien, studying humans, and making assertions without really understanding the nuance of the game playing out before them.

Lets start with some facts:

1) yes, malware can allow attackers to view streams emanating from the webcam.

2) With current PC design, under standard circumstances, an attacker CANNOT access your webcam without deploying malware or otherwise tricking you into executing malicious code on your system. Some software used by schools or enterprises to keep tabs on laptops they issue may blur this line, but in that case that software is the malware.

3) without installing malware, a well-situated adversary may see traffic you send or receive as it passes across the network, but they have no insight into your PC itself, nor control over it. This is why keeping your system free of malware is important.

4) Browsing the darkweb is a bit more prone to malicious content (content that tries to install malware on your system; aka drive-by downloads) but no more so than browsing for free icons/wallpaper, or images of an adult nature.

so, to sum up, the deep dank places in the Internet are more lawless exploitative and more caution and common sense is required. That said, the assertion in the quote is laughable, because there is nothing about the darkweb that provides an adversary more control over your system than surfing the standard internet, and using the internet does not, in normal circumstances, allow someone access to your webcam.

After all that, I do recommend you put a piece of tape over your webcam. It has nothing to do with Darknets, but simply with malware in general. Same reason FBI director James Comey does: http://www.npr.org/sections/thetwo-way/2016/04/08/473548674/why-the-fbi-director-puts-tape-over-his-webcam