Like so many folks, I myself don't even bother reading through legal mumbo-jumbo in software license agreements and just click the 'Agree' button
A trained professional—lawyer and developer Robb Schecter—took it upon himself to read through Apple's end user license agreement for El Capitan to spell out any limitations in plain English so you don't have to.
You don't own El Capitan per se when you download a copy of the operating system from the Mac App Store: instead, you're actually borrowing it and Apple still owns it.
This shouldn't come as a surprise: that's how software has been distributed for decades. But, I doubt many people are aware of El Capitan's limitations pertaining to virtualization, business use and more.