Sony feels its position in the market is strong enough to where it doesn't have to "buy outright exclusivity".
Speaking with CVG at gamescom 2014, PlayStation Europe boss Jim Ryan said the main reason is due to having a "large and very powerful network" of studios all its own.
This combined with third-party partnerships where it makes sense, such as with Activision and Destiny, benefits the consumers
"When you complement those two things we think that gives us a pretty complete position in the market," said Ryan. "So do we feel the need to go out and buy outright exclusivity? Probably not.
"You saw last night [at Sony's press conference] that before the media briefing we showed updated videos of games that we had revealed at E3. That's because we wanted to keep the show itself full of new, fresh things. We think that gave us a good, strong, convincing portfolio of exclusive stuff and we're happy with that."
Ryan's response was over CVG questioning whether Sony had a stance on securing triple-A exclusives, such as Microsoft's timed partnership with Square Enix on Rise of the Tomb Raider.
You can read the full interview with Ryan through the link.