Source that PS5 will play ALL PS4 games, please!
Source that most PS4 games won't need any patches or fixes to run on PS5, please!
These are just assumptions and Sony's current statements are speaking a totally different language... I really hope that they are just miscommunicating, since I want to replace my PS4 with a PS5 as soon as possible (and I don't have infinite HDMI ports + space to keep them both connected).
And no one said that quality assurance is a bad thing.
Guess what: Microsoft does that too: https://news.xbox.com/en-us/2020/05/28/xbox-series-x-next-generation-backward-compatibility/
"With more than 100,000 hours of play testing already completed, thousands of games are already playable on Xbox Series X today, from the biggest blockbusters to cult classics and fan favorites. Many of us in Team Xbox play on the Xbox Series X daily as our primary console and switching between generations is seamless. By the time we launch this holiday, the team will have spent well over 200,000 hours ensuring your game library is ready for you to jump in immediately."
“We believe that the overwhelming majority of the 4,000+ PS4 titles will be playable on PS5.”
Believing something is no guarantee, especially if two months later they only "strongly recommend" developers to add PS5 compatibility to their PS4 games:
“We’re currently evaluating games on a title-by-title basis to spot any issues that need adjustment from the original software developers.”
So Sony only tests the games, sends the report to the game developers and hopes, that the game developers fix the issues on time... preferably with enhancements.
On the other hand, Microsoft seems to be much more involved into their BC process: instead of fixing games on title-by-title basis they are tweaking the groundwork for all BC games to lift the burden from the developers in many cases. Some enhancements are also already provided by that foundation. And (according to the statements of Microsoft), that way seems to work so that already over 1000 legacy Xbox games "were tested positive".