That might not be a full-time goal. Some want a machine that works on the move but can be expanded to bigger screens and such when at certain locations (office and/or home). A laptop and dock allow this compromise.
It is a compromise, not one suitable for all. But it is the list inconvenient option for many.
I wouldn't say "some". Probably 90% of developers I know require exactly this, in fact off the top of my head I can't think of any who don't. Even the permanent, full-remote, no-really-there-is-literally-no-office types want to sit in a different room sometimes or work from a coffee shop.
It's pretty rare to have a "workstation" setup that cannot be moved.
And good luck getting anything close to RTX 3090Ti performance in a laptop. It'd basically be a toasted oven on your lap.
Desktops can just sink a ton more heat, and as process shrinks and die size increases have gotten us less and less additional performance each year, we're just pushing power up to the point now where a TOTL gaming desktop is pulling close to 1KW. A laptop will never come close. If you really do want to try a literal desktop CPU in a laptop, there are mfgs like Eurocom and Sager that will sell you one, just don't expect it not to throttle a lot under actual heavy workloads.
Wait, what? Are you like cryptomining or something? That's actually insane. I charge two electric cars at home, work from home using a powerful workstation, and my electricity is about £100/month. How do you manage to spend 800 euro a month????
I find it surprising that the appeal of the above would be confusing for anyone.
Sure, you could buy a separate desktop for that, but if you also go portable, don't want to bother with some kind of online sync solution, and want to move between laptop mode for on the go and something docked to big monitors and a no laptop keyboard/mouse for when you are at your primary workspace, getting a good laptop plus a dock rather than spending more for a laptop plus a separate desktop which makes you have to compromise on syncing somehow makes a lot of sense.
(Obviously, if you need desktop processing power, thermal envelopes mean that laptops aren't going to be competitive. But if that's your need, you aren't going to be looking at laptops, and how to connect peripherals isn't going to be your limiting factor.)
The only things that move around are my laptop and I. I don't want to carry around a desktop computer and plug in power, screens, and USB hub every time I switch desks.
