A question about supers
I'd say it's not so, historically at least. However I see where this perception comes from because it doesn't help that certain recent franchises can't write a good character to save their lives: it's easy to make Boring Invincible Heroines, but a good character you might actually care who happens to be awesome takes effort.
We're living in a time of creative suck in the supers genre where no one can turn out anything but Mary Sues (there are exceptions, always). But characters who can never lose are BOOOOORING. Characters who completely defy the mechanics of their own universe can be interesting, but when it's just "I'm like a predecessor character but better in every dimension without lacking in others!", it is not going to keep the attention of people who actually care about that universe, setting, etc.
Part of what you're seeing is certain characters get new and derivative versions because those characters are so old they want to expand their universes, and also the writers want to try new things using some aspects of that character but not others. Also the longer it goes, the more things are tried. A cheap trick to try to make the audience care about the new character is to go "Uh, she's... more powerful than the original, yeah!"
This happens to male characters too, like I do like Miles Morales, but depending on the exact version you're talking about he's just got straight up better powers than Peter Parker. It's a franchise wide power creep, sometimes.
Occasionally though, you get a Spider Gwen, where the new character isn't more powerful per se, but the new personality and situation presented by the new character having those powers but being a different person (i.e. an outgoing teenage girl got the spider powers instead of a nerdy, bookish teenage boy) is compelling by itself because someone was actually trying.
But sometimes, you get Super Girl, where the writers don't know what to do with her so they go "Uhhhh... she's... actually more powerful?" Granted, at least with Super Girl they thought of a good reason why that's true, but they also completely ignored the consequences (remember kids, what happens when Superman absorbs too much energy from the sun?).
See the way to do this, if you just want a distaff counterpart who's flat out better than the original, is Red Lantern Supergirl. Yeah, she's better and more powerful, but there's a twist and it comes at a price too dear. That's actually interesting. But again, it relies on someone actually caring enough to try.
Another aspect of this is a lot of these tend to become secondary tier characters who have their followings (I freaking love Power Girl, sue me), but they don't tend to be going concerns in the books all the time. When a character has more presence and more gravitas, you can have them "lose" occasionally and not make the character look weak or ineffectual. When a character gets less "screen time", they have to win to show off why you should care about this character.
Now there are exceptions, such as Barbara Gordon, where the writers realize, hey, we can make our secondary character more interesting in her own right and not just derivative. Barbara Gordon was allowed to "lose" and we got something new and interesting and engaging out of it! We got Oracle, who is physically inferior to Batman, but I would argue is actually exponentially more effective at fighting crime because she does it the smart way, but the reader knows she's vulnerable so it keeps it interesting. See how much better that is than "she just becomes Batman, but better." Of course... they had to roll that all back and now she's not as interesting any more, but what can you do.
Old School characters who were female characters to begin with tend not to get power creep, or at least not too much, because they're not trying to distinguish them from a male predecessor.