But they already do have a big first party game releasing before BF: Forza Horizon 5. If they didn't, I would have agreed with you. Forza Horizon is huge. FH4 is actually more popular than Halo MCC and Halo 5 if you look at Xbox's most played games.Xbox first parties have historically always launched before BF. It's a huge day to sell not only games but also bundles, limited/collector editions, merchandise and so on.
Besides, there isn't enough stock of XSX to sell on Black Friday anyway.