Once upon a time, this was a very strong argument, the architecture of the hardware and software of personal computers were just so different from each other.
Now the processor and GPU architectures of the consoles are identical to what can be found with PC.
On the software side, there are differences mostly due to Sony's self-inflicted decision to continue to have a proprietary graphics API, though if you use Unreal or Unity, then you don't have that much to worry about.
On the UI side, supporting keyboard+mouse players in addition to controller players and the associated 'button' indicators having to change based on which controller scheme and model are in use would add some too.
So the fixed-hardware facet of the platform doesn't matter specifically so much as people aren't doing the same super picky tricks they were doing decades ago that demanded super precision. The choice to have distinct APIs and to have many of their games similarly make in-house game engines do make PS5+PC more complicated versus Sony embracing Vulkan or their game developers using a cross-platform game engine from the onset.