The very concept of technology groups in EU4 is a blunt and abstract way to make games play out more-or-less historically, with Europe usually dominating the world by 1800 barring player intervention. Trying to accurately model technology spread in a videogame is an impossible task, which is why the game uses such a blunt and silly tool for the job. Historically, no country has ever westernized like in game, because the very idea of tech groups is a fabrication for gameplay purposes. And part of making the gameplay of tech groups work out in a fun way is to let players (and some lucky AI) overcome those difficulties with a bit of work. An acceptable reason to make westernizing harder or easier is to maximize gameplay, not to try to fulfill any sort of historical goal (because again, tech groups themselves are not historical).