It's not mindless brute-forcing, the details of the architecture, data, and training strategy still matter a lot (if you gave a modern datacenter to an AI researcher from the 60s they wouldn't get an LLM very quickly). The bitter lesson is that you should focus on adjusting your techniques so that they can take advantage of processing power to learn more about your problem themselves, instead of trying to hand-craft half the solution yourself to 'help' the part that's learning.