People act like bigger screens and no headphone jack is some conspiracy. It’s a competitive market. Small phones exist. Headphone jacks exist. They’re obscure because they don’t sell well, because that’s not what most people want.
It’s frustrating when you have an uncommon desire for a mass market product, I get it. But the answer to “why do they” is pretty obvious if you can understand that you’re not representative.
By that metric they shouldn’t release a folding phone at all, it’s a very niche market