The brand was built on multiplayer as well. Let's not pretend that games like Socom, Killzone, Resistance, MAG, Warhawk, Motorstorm, Driveclub, GT etc didn't have dedicated fanbases.
It was only during PS4 that Sony really focused primarily on singleplayer games and even then we still have Killzone Shadowfall, GT, Uncharted and Ghost of Tsushima with decent to great multiplayer components.
The only one that got pushed back and ultimately canceled was Factions 2.
All these games are part of what made the Playstation brand strong, but Sony relied more on 3rd party for Gaas last-gen.
They are just picking up where they were slacking with PS4. It's not something new to them.