You might want to find ways to optimize it form non-technical aspects, such as, how to get more users, how to write better titles, etc. But there's nothing that is technically challenging about it.
I'm sure there are even more technological advancements that can be made - and I suspect there always will be.
I'm not saying that it is currently ineffective, just that it isn't solved - meaning that there are still solutions to improve efficiency and efficacy. I actually see 'solved problem' as a kind of defeatism.
In reality it's mostly just dark pattern marketing.
But, yeah, it can be used for nefarious purposes. In fact, it probably will be. Hidden under that will be good uses.
I suspect there's going to be constant innovation. There are people who thought that personal transportation was a solved problem back when we rode animals. These days, we are looking at an EV revolution and SDV somewhere in the not-too-distant future. Along the way, it hasn't been a solved problem, even though it looked like it was.
I guess that's what I've been clumsily trying to say.
I'd agree with them, by the way. I don't think we really have that many solved problems. I'd consider that to be hubris and see many things that can be improved on, across the spectrum of ideas and implementations.
In fact, I'm hard pressed to think of much of anything that is a solved problem. Most everything can be improved.