Is CDX really that difficult? It's not one that comes to mind when I think of harder Castlevania games. The Dracula fight is even a cakewalk if you have an ax and stay on the lower pillars.
I agree with you and was talking with people about this on discord recently. Apparently nowadays you have to be careful what you say on the topic of video games being a challenge because some people think they should be able to beat games whether they take the time to learn to play them properly or not. And coming to the defense of a game some others may think is too hard can get you labelled a "gatekeeper".
I can still love cv3 despite that it still haunts me to this day as I've never finished it. The challenges are what makes a game a game and it's part of the art of game design. I haven't beaten CV3 yet because I haven't worked hard enough on it and I don't deserve to beat it yet, and that is fair and cool with me. One day I'll get there.
When I got to Dracula in DX I tapped and handed the controller to my brother out of frustration and he beat him. I was kicking myself about it, but I didn't earn the win myself and that's fair. He beat him in 3 tries. So it wasn't the game, it was me throwing a fit and not thinking clearly to do the job myself.
Input equals output. Its not gatekeeping to use walls to build a maze. Players that don't want to put in the input can complain for walls to be knocked down so they can get to the cheese. But the more walls they knock down, the less of a game they have. And it definitely can get to that point because no matter how easy a game is, it's never easy enough for everyone.
With all due respect to players of all skills, this is just a fact that applies to all areas of life, games included.
Overcoming a challenge is what makes a victory special and sweet. People use the excuse of "I don't want a challenge I just want to know what happens". Sounds like what they really want is a movie and not a game at that point. That's certainly not what retro games are about anyways.