From the story, ''AnandTech has been profitable since its inception; it’s been on a great growth curve these past couple of years and we’ve always been able to do more with less, but lately there’s been an increased investment in high quality content.''
Additionally, ''...they [Purch] have a sustainable business model, are profitable and have the sort of reach AnandTech needs to really hit the next level.''
If the business is profitable and has been from its inception, it could be possible investors have had a sizeable return on investment. If this is the case and earnings are steady, it's a large risk to transfer ownership to a new stakeholder for the sake of 'growth'. For example, new ownership and more users may alienate the existing, profitable userbase.
However some web businesses may require 'user growth' as a minimum industry requirement to stay alive.