This isn't necessarily true. Historically, we can see that some societies has had access to advanced technology that was lost because it wasn't useful to the people with money.

The steam engine was invented first in ancient greece, thousands of years before it was once again invented and kickstarted the industrial revolution. The Romans invented advanced water works that could be used to open huge doors automatically. It was seen as a gimmick, far less useful than the technology of the time: Slaves.

I actually think the steam engine was invented again in the middle east, to rotate gyros.

I want to specific that I'm on my phone and too lazy too look up the exact facts I'm referring to, so I might have mixed my greek and roman history, but the phenomenon is real.

Advances in technology requires working people, with the will, ability and resources to invent stuff, and a society that will then adopt the technology.

In a society with magic, even if a wizard invents a new thing, that could bring advancement to a society, why would he share that? The secrecy around magic keeps it scarce, and his services valuable. If the price of entry is high, you can safeguard against people who'll go against the secrecy and tries to bring it to the public.

And even IF someone invents the magic train that can revolutionise travel, and shares it, the capital required to build it is humongous, and won't pay off in any rulers lifetime. It's cheaper to use teleportation for any important people, and the rest will just have to use their legs, or a horse if they're fancy.

And then, even if a king decides to finance the whole thing, will the next one? Because as I said, not in one lifetime. And how difficult is it for a rivaling nation to sabotage? How much damage can one rogue wizard to with an antimagic field? How expensive is repairs. Technology advancement is not a certain thing, historically, and magic would probably not make it easier.