I think the general vibe from the OP comment is that a lot of the fun with low spec and retro hardware is working with restrictions and squeezing new and novel amounts of use out of old hardware. But once you get to the stage of putting a much much more powerful computer in the cartridge, you come to the realization that you can do basically anything at this point and treat the gameboy as a dumb display/input device. Now it's just regular embedded programming.
Not to detract from the project, it is very cool. But the excitement kinda feels dwindled when you realize that you now have limitless power and ability. It becomes just regular programming rather than a puzzle.
For some perspective, even the oldest network enabled addons sold for the GB/GBC did the same exact thing (such as the official Mobile Game Boy Adapter). It's more like, without doing it this way, it's not even possible.
I don't see the complaint as "it's wrong to use powerful chips in a cartridge". As has been pointed out, even contemporary cartridges did things like that.
I see the 'complaint' is that there's a creative/artistic appeal to seeing what can be squeezed out with limited/constrained resources.
Or, at worst, does it make sense to use an old console like the Game Boy if you're going to use such a fancy cartridge?
I'm reminded of the MythBusters episode where they tried to make a cannon from a wooden log. They resorted to using modern power tools. "I'm not doing anything they wouldn't have done if they had access to these tools!".
Not to detract from the project, it is very cool. But the excitement kinda feels dwindled when you realize that you now have limitless power and ability. It becomes just regular programming rather than a puzzle.