Kudos to the Giants because they've always been hip to their tech surroundings. Recall they wired up the stadium a few years ago for Wifi which everybody scoffed at then (can't live without now). New scoreboard, etc.
I'm sure a not-insignificant portion of their fan base works in the tech sector.
And for AMD, it's a smart hey-we're-still-alive event in front of a hip crowd.
Bottom line, what will make or break this day is whether we beat the Dodgers.
I also taught my boys how to build a PC when they were young, and by high school, they were building insane gaming machines and knew all the overclocking tricks. My oldest even had a refrigerator PC case for awhile that cooled the CPU to 0 C before booting!
Besides being a fun and educational father-son activity, it had other advantages. My oldest son always stayed informed about the latest graphics cards, etc., and was willing to put in the time to find the best online prices for each component -- so he became the PC builder for everyone in the family, including my own new machines.
I think on average, he could assemble a PC in about 30 minutes, and nearly half of that time was just connecting wires to header pins on the motherboard for things like HDD and Power On LEDs, front panel USB and audio jacks.
I don't think this marketing idea is too late, but I doubt it will make any difference in sales. Desktop PCs are still popular enough, especially with gamers, but I think the percentage of build-your-own PCs relative to total desktop PC sales is rather small.
I've been building PCs since the 1990's, now my oldest sons have followed suit by building their own gaming PCs. It's mostly integration, some electrical and mechanical assembly, and loading SW drivers plus your OS of choice.