I was going to say "true".... but then I thought about my boss and it got a little more complicated...
In my day job, I make edutainment. My boss has launched a pretty successful kids edutainment franchise, without really having any particular background in writing and with what she'd profess as "absolutely no drawing skills". Her approach to making a book is to basically get input, and help from a lot of other talented people; she'll find people with expertise in whatever she's writing about to give advice, she's named as the writer on the front of the book, but she's not scared to find writers to help write harder passages of text, or to take onboard recommendations from the editors, and of course the illustrations and design work are done by other people too.
At first, this approach angered me, because of course it would; my way of making a comic has always been "If I need to do something I can't do, I should learn to do it myself!" Meaning that after years of training and reading all the books (aw yeah, Autistic hyper-focus), I now draw, design and write to professional standard and can make a print book solo if I need to.
But the thing is... my boss' approach works? She has also managed to make books; well received ones, because even if she'd happily admit to not being the world's top writer, she has an amazing talent for connecting with talented and clever people, and for selling and promoting products. She knows how to come up with a series concept that makes investors and industry people look up with dollar signs in their eyes.
So I think my stance is like...
"You can be the ideas guy... but you'd better have very sellable ideas, means to realise them in a way that looks good within the budget you have, know what steps are required to do what you want to do, and be an absolute genius at selling what you're doing to people who can get you somewhere with them."
But as was said in the opening post, most people who want to be "the ideas guy" don't have that. Their idea is something uninspired like "A dark retelling of Alice in Wonderland" (this became an in-joke with my comics and games friends, that every useless ideas guy you meet wants to pitch a dark retelling of Alice in Wonderland), or just some generic Isekai story about a protagonist who totally isn't a self-insert but happens to be just like them... And then they come marching onto the forums like "Yeah, I need like... three line artists, an inker, two colourists, a writer, an assistant writer and an editor to make my amazing new webcomic. I'll pay you when we sell the rights to Netflix. Which I think we can do." They don't know where to find people so ask randomly, they don't know how to organise a webcomic or even what a realistic webcomic team looks like, and you can be assured they wouldn't even know how to pitch to Netflix even if they had a snowball's chance in hell.
And I'm sure those useless people are looking at AI and salivating like "aha! At last! I can make my thing without needing an artist! I just describe my brilliant idea to it and it makes what I say!" Because they miss that what an artist brings to a comic or even to a novel cover isn't just the ability to draw. Adding some art will definitely make a thing better, and if the art has nice rendering, yeah, that is an improvement over some rough doodles for sure.... but it'll never be as good as having somebody make just the right art. When the art style perfectly matches, and the artist is evoking the perfect energy for the story and their composition choices and the expressions they draw aren't just generically pretty pictures, but feel like real illustrations of the characters and scenes, something magical happens. It can only happen if you pick the right artist and trust them to add their voice. That's where you get a combination like Roald Dahl and Quentin Blake; creators who both have a very loud and distinctive voice of their own and together it's like combining John Lennon with Paul McCartney; you get magic.
You can't get magic if you're too scared that the artist's work will speak louder than yours. The timid choice of letting a computer generate you an image of a generically pretty face staring out into space, or somebody just off-centre in a vaguely painterly environment with their back turned can work, but it can never sing. AI can only fill a gap where an artist should be, and those rare effective ideas people know that. Steve Jobs understood fundamentally that he needed people like Steve Wozniak, and that his role was to make all these brilliant people work together and to sell it.
I think a person can be a successful "ideas guy", but they need to be a BOSS. They need to bring overwhelming force of personality and leadership, and the ability to attract talented people to them, and to have the person with just the right writing or artistic voice fill the right roles to get a working product, and then to sell the crap out of it. The good "ideas guy" has the power of charisma, and is a rare being indeed; rarer in my experience than even good artists and writers. AI just isn't a good fit for them because they need to have something unique to sell, and where the style really fits their pitch. Anyone can use AI and get the same sort of quality of result in the same sort of style, and you just end up throwing loads of time and money at it (and time IS money), at which point any person with some smarts will go "I could have just found some little known artist and commissioned them and then bigged up the artist as part of the story that sells the whole package."