Whether or not technology would develop in a society with access to D&D-style magic is a complex question, but I think an economic case can be made for tech. Here’s a possible way that plays out (one of many, obviously):
From a typical player’s perspective, magic is very common, because they’re playing adventurers, and magic is concentrated among the adventuring population. Even there, direct access to magic is not universal; generally speaking, less than half of the adventuring population are casters. Among the general populace, magic is spread more thinly: small communities may have only one or two priests, and may or may not have a minor arcane caster as well.
Given a medievalesque setting, most of the population is presumably rural, so they are subject to the above magic-per-capita limitations. For them, magic is scarce, and therefore, it will generally be expensive in one way or another: tithes or donations in return for the priest blessing their fields, bartered goods or services in exchange for a hedge wizard’s potions, and so forth–and if you’re not on good terms with your local priest or witch, magical services get even more expensive, if they’ll provide them at all. If something is expensive, you can bet that someone is going to try to find a cheaper way to do it.
“Pay the priest for a blessing? Hell, no! See how green yon pasture be? My cows can ‘bless’ my field just as well as the priest!”
And thus, fertilizer is discovered. Technology advances. It would likely advance more slowly, and in fits and starts, in a magical world, but the price and accessibility of magic would still drive it forward. Social structures might stagnate, with the concentration of magical power in the hands of the upper echelons, but wizards and priests like cheap stuff, too–eventually, an industrial revolution would come.
At that point, the question becomes social and political, and hinges heavily on how benevolent the magic-wielding ruling class has been. As long as the general populace is basically satisfied, things chug along with a magical upper class and an emergent manufacturing class. Things shake out into technology providing better access to more basic goods, while magic-wielders continue to be high-power, highly paid specialists, the rock stars and neurosurgeons of the world. Once the dust settles, tech returns to its pattern of intermittent advance, while society remains a mix of pseudo-feudal and city-state politics.
If they’re not so benevolent…they discover that mass production includes the possibility of mass production of weapons, and you get a different kind of revolution. Magic gets suppressed, temples get closed down, scrolls get burned, and tech becomes the primary way forward. Magic use goes underground for a time, but eventually re-emerges as a useful tool in an uneasy balance with tech-based firepower.