Youre not completely wrong but the main influence was probably Youtube. The sad thing is 16:9 phones were the peak of phone evolution, everything after/longer than that is hardware designed specifically for doomscrolling.
I still have my iPhone SE 1st gen with the perfectly ratioed 16:9 display, so nice not having black bars, while also having room to put my thumbs while I hold it in landscape watching a video.
My main phone, a Pixel 7a, is better in every way but my goodness holding it while watching a landscape video is terrible because my fingers keep occasionally touching the edges which are registered.