Playstation certainly delivered a much better early environment for developers. The PS4 development environment has been said to have carried over very smoothly to PS5, and there was a comfort level there. DX12 Ultimate and RDNA2 hardware weren't finalized until March of 2020, which Microsoft apparently waited for before finalizing the development kit. Some developers got the final kits in July and August, which is the same time it appears most of the consoles were manufactured.
So while "the tools" have now been memed to infinity and back, it does seem like Microsoft was late in delivering the goods for Xbox Series consoles to development teams. That shouldn't be seen as an excuse. That's a mistake that Microsoft should be criticized for.
Along with Sony's custom I/O interface, they also have some advantages built in to their GPU design, aiming for fewer compute units at higher clock speeds. Microsoft aimed for a wider GPU with more compute units, but with lower clocks. They also have the same 64 GPU ROPS as Sony. So, in real terms, in means Microsoft is at a disadvantage in regards to raw rasterization performance, particularly in situations where the engine can't keep all the additional compute units busy. ROPS are a fixed function unit, and 64x2230 is a bigger number than 64x1825, so Sony can push more raw pixels. That said, Microsoft may have advantages down the road when developers attempt to make more use of Ray Tracing, VRS, Mesh Shaders, and any machine learning related tasks that might arise if they are able to adopt AMD's competitor to DLSS. Because 36x2230 is a smaller number than 52x1825 on the compute unit side of things.
I still maintain that we are most likely going to see developers aim for parity. There's very little incentive for third parties parties especially to optimize beyond reaching acceptable performance on both machines.