Title? I don't need no stinkin' title.
To a certain degree I agree that you have a point. However, it's a huge leap to go from continual flame being somewhat common to magical John Deere tractors. There could be a significant level of magic but most of it would simply be conveniences and have only subtle impacts on society. You have priests and druids that get real results when they bless the fields, but it still takes manual labor to plant, tend and harvest. People can't suddenly get rid of the ox and plow.I've got to agree that CF would have major worldwide social impacts. Impacts that generally would cause a disconnect in how most fantasy worlds are portrayed. Doesn't mean we shouldn't consider such changes in our worlds, just that in general we don't. The other thing, we generally portray our fantasy worlds in a relatively stagnant social and technological aspect.
Look at canon for the various worlds, how much "technology" or social progression has actually happened? FR, GH, DL? Nope, Eberron is the only one that has any type of historical technological advancement. Why doesn't the Realms have magical plows equivalent to a real world John Deere? I mean if they farmers have been farming and their has been magic for 10k years, why not? Even if such a thing costs 100,000 GP, you can justify it the same way you can CF.
Sure, the first step might be a safe and reliable light source, but the next might be food preservation. Then sanitation. At that point life spans increase and birth rates go up followed by individual productivity doubles. Now you have 20% of the population involved in food production instead of the medieval 95+%.
All that extra time and resources... lots of that is going to go into law enforcement, so that the tax payers are safe. And then lots of that is going to go into a military, so that commerce is safe. And with all that excess population, you are going to have to settle all those wild lands. Which means the military is going to clear out all those "old dungeons" and adventuring sites. And since soldiers don't like to die, after a thousand years, soldiers are not going to be using longswords and wearing chainmail. And why would adventurers use such archaic and inferior devices?
Look, trying to guess the impacts of technology on a fantasy world means that you can suppose just about anything. Will every peasant house having a CF break your game? Nope. But it's just one more disconnect in our fantasy. There are plenty already. Use the ones you want, ignore the ones you don't.
You can have magic without having modern levels of techno-magic in an Ebberon-like world. Yes, people have light at night. It's nice. Magic would make life marginally easier and decrease child mortality, but it only changes the fabric of society as much or as little as makes sense for your world.