Yep. It’s a bit hard to fathom today, but in the Middle Ages few people had the ability to read and write, mostly either learned monks and clergy, or those wealthy enough to be taught by them. With such a small pool of people, it’s comparatively easy to influence the prevailing spelling through the actions of a few.
Key words being “current supply”. There are major moves being made to change this. Supply and demand need to grow at the same time if this is to work though.