I always assumed that was the reason too, but it feels like there was really only a narrow window when there was a significant crossover between monitor panels and TV panels.
Most all new TVs are 32" or larger, so that's not going to widely impact what 20-27" monitor panels can benefit from. Even when smaller LCD TVs were popular, they were often 720p or 1266x768 panels, but most monitors were 1080p.
OTOH, maybe it was more of a second-order thing: people were primed from TV and movies to expect wide-format content, so monitor makers had to produce products that satisfied that; people don't like letterboxed/pillarboxed displays.
Don't underestimate the effects of tradition. "We do things this way because we do things this way" is one of the strongest effects in technology.
Secondly, I suspect, but do not know, that there are effects here of making big panels and then cutting smaller panels around the edge of the large one.
Most all new TVs are 32" or larger, so that's not going to widely impact what 20-27" monitor panels can benefit from. Even when smaller LCD TVs were popular, they were often 720p or 1266x768 panels, but most monitors were 1080p.
OTOH, maybe it was more of a second-order thing: people were primed from TV and movies to expect wide-format content, so monitor makers had to produce products that satisfied that; people don't like letterboxed/pillarboxed displays.