I mean, even just assumption based on the fact that it was the case every previous time is kind of enough.

But the main reason PC ports come out after console is, tuning for a variety of hardware. PCs are millions of different things. Consoles are like 5 things. Tuning for them is much quicker.

The more complex a game is, the longer the gap between it being ready for release on consoles and it being ready for release on literally anything between the minimum requirements they are willing to target and the highest end hardware currently available plus an attempt to future proof it for stuff that doesn't exist yet.

The exact timeframe can come down to an exclusivity deal, but the time isn't wasted.