Yes, it's been a thing for at least a decade, I imagine it helps with pre-sales online, though it may just be offered as a convenience. It really does help keep the movie from unexpectedly being a lousy experience; if you're stuck in a crappy seat, or your family can't sit together, it's because you picked those seats. As someone else mentioned, it also allows them to bring you dinner and provide that upsell as well.

Even our small independent theater in town has reserved seats, some of which are couches.

> it's been a thing for at least a decade

Maybe in fancy theaters, but in most places it started during covid (and just never stopped)