I think at least at the early stage of EU4 time period, Western Europe still had not reached the turning point making them massively superior comparing to the Muslim and Asian world (except the nomads and tribal society maybe). So if a Muslim or Asian nation actually can do everything right and be lucky enough from the beginning, they should have a chance, though not easy, to stay competitive comparing to Western Europe throughout the game. However, I think the westernization option shall still be there but harder to achieve. It allow you to catch up if you are far behind.
I think this way also offers some variety in gameplay. Playing as a non-western country, you can dedicate most of your resource to try to stay technologically on par with Western Europe. Or you can put your resource somewhere else and also prepare yourself for westernization. Still can't say it is very historically correct since the westernization in EU4 sense (country actively trying to switch into western way, rather than becoming colony of western country) outside of Europe doesn't really happen in the game's time period I think. (I am thinking of examples like Japan and China).