You have to remember my frame of reference. I'm an old guy.
Back in the 1970s Mantis' powerset was that of a street level hero. Her training by the Priests of Pama aside, she was really just an empath with martial arts mastery specializing in using pressure points to advantage her attacks. It wasn't until later -- I want to say around the 90s -- that Mantis as the Celestial Madonna showed far greater abilities than that -- like the power to travel between planets spiritually and creating a new body for herself out of vegetation.
Ghost Rider was a stunt cyclist who made a deal with Satan. It wasn't until later that Zarathos was named, and at that time, he/it was perceived to be a minor demon. Certainly nothing on the level of Mephisto, like he/it is now. In the early days the perception was that it was Satan, but Johnny wasn't necessarily about to run off and battle Thanos seeking revenge. No, he stuck to mostly low level villains and cultists, except for when he joined up with the first team of Champions. But I guess we don't need to discuss GR, because Marvel made it easy for us. They didn't call him
Cosmic Ghost Rider for nothing.
And while I agree that Spider-Man, Black Panther and others all only wielded cosmic level power situationally, it counts.
I'm not knocking it. No one likes characters that are forever limited by their native circumstance or abilities. Sometimes the only way to see characters in a new light and see how they'd handle the yoke of even greater responsibility is to give them greater powers, no matter how briefly.
Before the unfortunate retcon, we all saw what happened to Jean Grey when she became the Phoenix. I'm curious to see how Echo carries the mantle now.