Then why do I keep encountering explanations that the "magic" and "sorcery" featured in the MCU is basically alien technology?
Because the MCU was made with the understanding that the general audience had different expectations and sensibilities than the comics audience. Comics readers are used to their total hodgepodge of genres, where sorcerors and literal gods and demons can coexist with superscience and aliens and monsters and street-level vigilantes and straight-up cowboys and everything else. But to more general moviegoing audiences, seeing sci-fi and fantasy in the same universe could be confusing. So the makers of the MCU started out slow in order to ease the general audience into the sheer eclectic weirdness that comics fans take for granted. They started with the Earthbound, superscience stuff like Iron Man and the Hulk, then rationalized Thor and the Asgardians with a sci-fi explanation so they'd fit into a sci-fi universe. (Also, they probably treated the Asgardians as aliens rather than literal gods so as not to offend religious types.) But now that the audience has gotten more accustomed to the general freaky weirdness of Marvel's sci-fi aspects, they're ready for the MCU to take the next step and introduce them to actual magic. The movies are doing
Doctor Strange, AoS is doing Ghost Rider, and the Netflix shows are about to introduce Iron Fist and his mystical chi powers, after already teasing us with the Hand and their resurrection abilities in
Daredevil. (Indeed, the Netflix shows followed the same progression -- they started out with the least superpowered hero, even toning down the portrayal of Daredevil's power to less of a "radar sense" and more just using his surviving senses really well, and then they introduced more superpowered characters like Jessica Jones, Kilgrave, and Luke Cage, and they've saved the outright mystical powers of Iron Fist for last.)
The DC television universe also used this approach. First they started with
Arrow, a grounded, street-level vigilante show. Then they started to bring in science-based superpowers with the Mirakuru serum, and that primed audiences for the Flash and a world of metahumans and superscience, and then they started to hint at the paranormal with the Lazarus Pit, and then they brought in actual magic last season, as well as time travel, reincarnation, aliens, pretty much the whole jumble of genres. But they needed to start out grounded and ease the general audience into the weirder stuff one idea at a time.