I’ve been making up games and rules since I was a kid. The thing I’ve always understood is that while you are free to make anything you want to be possible (“This is magic”), you should still try to have internal consistency. If your game is meant to be an alternative version of reality, like a medieval analog of our world except magic exists, then it should still conform to reality outside of the alternative aspects presented. It’s fine to say “The king was assassinated by a spell,” but you better have some sort of logical reasoning behind how that spell works if you expect your players to be able to investigate the assassination.
Given the bugbear in the room regarding the concept of summoning spells, the best way to reconstruct them is to start with where we got the concept from in the first place: consorting with demons. Accepting and henceforth ignoring its religious origins, the early demon summoning spell itself was a drawn-out ritual, requiring obscure research and meticulous preparation. The spell was intended to summon one specific creature, that would be trapped by the use of sigils and runes, and obligated to negotiate for its release by performing a service for the wizard. There was an unstated understanding that, much like the power of words used in spells, words used as vows also had power, and that the Universe enforced or punished those involved. Cf to 1e spells Suggestion, Geas, and Quest. Note that the service might still not have been entirely paid for by releasing the demon. Either way, the two big takeaways are that it was a tremendous effort, cost, and risk to the wizard, and that it was a unique event (although there might develop a “professional” relationship between the demon and wizard).
1e at least had it as a ritual spell with all the prep and risks. 2e pretty much avoided any talk of demons, having kowtowed to religious fundamentalists. So too with demon summoning, removing (at least initially before its horde of
DLC handbooks were published) the 7th rank spell Cacodemon. Gate was already more of a generic “outer plane” summon spell, and so didn’t need further toning down. If someone can clue me in when TSR or WotC brought back demon summoning spells, I’d appreciate it.
Still, there at least was a bit of hope introduced in 2e, where in one of the MS descriptions was an indication that sometimes adventurers were whisked away, and not just monsters or evil humanoids.