Also, let's be honest: The vast majority of PC owners do not upgrade the individual hardware, they just go and buy a new PC. Most people don't own desktops any more, they use laptops. Everyone I know with a desktop is either a gamer or has a professional use-case (Programmers, Musicians who do their own mixing, Graphical Designers, that kind of thing).
Having to track and upgrade individual parts is a niche desire, one I definitely have but still a niche one. Most people just want to use exactly enough brain power to go "This one has a bigger number, so it'll do better computar stuffs".
Much apart from whether anyone would upgrade their PC (or laptop... to the more limited degree that relates to them), I would personally never suggest anyone would get a laptop unless they
will want to use it in an actual mobile situation. Apart from upgrading opportunities (which, as you point out, is well down the list of most people... at least at first), you don't get as good a value in terms of speed/capacity/etc. 2.5" HDDs cost more than their 3.5" equivalents, for the same size. The limitations of cooling mean that a laptop equivalent of a desktop CPU/GPU is in a more expensive package for the same cores*clock value (if you can even match it). A larger laptop screen makes the package disproportionately more expensive compared to an equivalent desktop screen (assuming you don't buy a separate one
anyway, for use when 'docked').
I speak as someone who has sold computers (new and recycled) to people. Everyone
wants a laptop, which I'm happy enough to sell if they
really want them, but if I enquire as to their motive it usually turns out to be some belief that they are getting
better hardware. (Occasionally it's so that they can tuck the machine away behind the easy-chair when not in use, rather than set up a dedicated computer station. A good SFF case and (these days) a light and thin LCD monitor can just as easily tuck away behind/beside the chair they're
always going to use their machine from, though.
About the only 'plus' to a laptop is that all but the lowest-spec recycled ones have integrated Wifi, while most desktops need a Wifi dongle or card inserting, accordingly. (Although I also suggest that it's better
if you can wire your machine, laptop or otherwise, to the router. Better speeds, more reliable, less susceptible to signal drop through a wall, one less thing to worry about regarding security, easier to trouble-shoot when it inevitably goes wrong, etc... but of course relies on being able to lay a cable between the two is necessary, which might be impractical if both ends aren't in convenient proximity and/or you don't own enough of the house to drill a hole in the wall/floor/ceiling.)
Still, The Customer Is Always Right. (After checking that The Customer Realises What It Is They're Being Right About, of course.) And I'm a stick-in-the-mud, myself, but I've only given people my opinions (where appropriate), not forced something on them that they don't want.
...but I fear I'm getting off-topic.