I use customer cast offs and even employee cast offs. My desktop was cast off by a customer because Win 10 ground to a halt. I slapped an ancient nvidia card in to get a couple of screens and popped in a cheap SSD. According to dmidecode it is a Lenovo from 01/06/2012.
My laptop at the moment is a HPE something ... HP 250 G6 Notebook PC according to dmidecode. I used to have a five year old Dell 17" i7 based beast but it ... broke. I whipped out the SSD, shrank the root fs a bit (with gparted) and used a clonezilla disc and an external USB link to get my system onto a Samsung EVO M.2 thingie from the SSD. This laptop was an employee cast off/
As is probably apparent from the above, I use Linux. I have some decent apps at my disposal but in general I don't need much hardware. Decent: RAM >= 8GB and SSD storage are key. I don't play games much. I've always specified 17" screens in the past for my laptops but now I have to use a 15" jobbie, that's becoming less of a hard requirement.
I am a Managing Director (small business - IT consultancy) but I do spend rather a lot of my time doing sysadmin and network admin stuff. I also do business apps. I once wrote a Finite Capacity Plan for a factory in Excel with rather a lot of VBA. Before you take the piss, bear in mind I used the term finite and not infinite. That meant that quite a few people had employment in Plymouth (Devon not MA) in the 1990s. I won't bore you with my more modern failures 8)
Anyway as you say, modern laptops are phenomenally powerful. Mine have wobbly windows 8) I can't be arsed with MS Windows anymore for my own gear - it gets in the way. Me and the wife said goodbye at Windows 7.
But in all reality, laptops are really, really powerful these days.