Sort of a dumb argument from the start since laptops have up to 17" screens and aren't so different from desktops. I think the real divide is between computers with full sized keyboards and decent sized screens compared to tiny keyboards and screens from larger tablet size down to tiny smart phone screens.
The full size keyboard and decent size screens aren't going away. They'll be around for a long time in some configuration.
For about 15 years now I’ve used a laptop.
When at work I plug it into a large monitor, which I use in conjunction with the laptop sitting beside it as an auxiliary monitor.
I also plug in a standard keyboard and use a wireless mouse.
For the life of me I can’t see how this experience is any different from using a “regular” desktop PC.
Except I can easily take the whole thing with me when I leave the office.
Cost is always a factor. Laptops can be double the amount of a PC. Many jobs are still at a desk. The laptop is needed for portability. If the job is static, why pay the extra cost?