I feel like Sony's overall philosophy is really to give developers control over what they make, more so than Nintendo or Microsoft.
For instance, when Naughty Dog moved on from Crash Bandicoot to Jak, and Insomniac moved on from Spyro, they just sold the franchises. Same thing seems to be the case for Jak, Infamous, and so on. Franchises that seem to last the longest are ones where the original studio is still involved like God of War or Ratchet and Clank.
Sony is more likely to keep the dev and be done with the IP, whereas Microsoft's philosophy seems to be to keep the IP and give it to a new developer, as they did with with Halo and Gears. When they need new IPs, their strategy of late seems to be to buy developers.
Nintendo's strategy falls somewhere between the two. They will generally have developers move on to different things, but also keep the franchise going with new teams. Like what they did with Luigi's Mansion 2, Punch Out!!!, DKC, and so on.
The strategies have their pros and cons.
I always got the impression, similarly to you, that Sony let their devs do their thing. Most creatives want to move on, eventually. Nobody wants to be known for just one thing and never evolve. Naughty Dog, as an example, moved on from Jak because they wanted to try something new. I like to think Sony MOSTLY respects the creators enough to not want to disrespect the IP.
And seriously, there's something of value to be said about knowing when it's time to move on. Uncharted is a great franchise but I'm happy to see them move on. I'd be completely satisfied if 4/Lost Legacy was the end of that franchise. I'm also happy if Bloodborne doesn't get a sequel. Not everything needs to be Franchised.
I got it all, baby!
PS4, Switch, WiiU, XBO, PC
Vita, 3DS, Android
Top 6 this generation:
Bloodborne, Sekiro: Shadows Die Twice, God of War, The Legend of Zelda: Breath of the Wild, Dark Souls III, Red Dead Redemption II