The entire ROM size thing was proven to be pretty much a lame, bogus technical reason to justify not supporting newer Processors. It was never a real problem to begin with, just an excuse.
Pretty much. AMD released a new platform with new functions and performance envelopes, like all companies AMD wants to make sure their products are used in their performative setting and without surprises that even if not their fault they don't have their rep tarnished by another party (whether they are a partner or not). Heck just in terms what Intel can get away with giving them the ammo for a lopsided slide can be bad enough.
Intel for multiple reason's has to be clear in the PR materials where and how they sourced their performance metrics (now they don't even have to have it in the slide but an embedded link). This means that the public is free to critique and generally Intel gets slapped if they twist the truth to much (like recompiling a benchmark with their compiler that based on whether it has genuine Intel tag or not it sends it down a performance path or one without many simd's. Letting the public run a 5950X on a B350 board, with thermal throttling limits, no PCIe 4, no direct memory access, and so on, the numbers would look so much worse and no amount of "but look at the footer webpaged. They rigged it to fail" is going to help as barely any body gets that far or cares enough at the end of the point.
Now look at Alderlake. Thread director meant almost all of the numbers for legitimacy needed to be taken from Windows 11. That meant any AMD comparisons had to be done in Windows 11. Then after the fact we are told about a bug in the scheduler that only affects AMD processors exists. Doesn't matter Intel now has the slides with crappy 11 game performance that will use till Raptor Lake.
I like using these because its just a perfect example of their direct competitor using a working configuration against them. But that's the point. It's why AMD and Intel both pushed away chipset partners. It's why NVidia puts so much into their FE cards when the cooling alone would cost the AIB's amost as much as the MSRP that Nvidia sets and will only let the initial reviews be on the FE models. Its about controlling the representation of the product. 300 series boards especially were all sorts of half baked and AMD didn't want their newer super competitive CPU's to be represented on those boards.