i think he's referring to the fact that you could boot on some models of the Master System without a cartridge and Alex Kidd would start. The game was literally built in the system.
A bit of both really. You could get cartridges for the Speccy but choice was limited and games were more expensive. Most 80s kids in the UK were used to having to wait several minutes for a game to load from tape, so the fact that you could just swap out the games on a console and play instantly was quite novel.