>>778470>Oblivion and Fallout 3.>Don't you constantly have to add new parts to play games?Not for games like Oblivion or Fallout 3, no. A laptop with an i5-8400H or i5-9400H processor will actually play games almost exactly the same as the desktop you posted, because it will have the same onboard graphics and a roughly-similar processor. The obvious proviso is if you do decide to get a graphics card, you need to either get a Thunderbolt enclosure (if your laptop has a Thunderbolt port) or a new laptop (if it doesn't).
>>778468>set your laptop down and connect an HDMI cord to the monitorsYou can actually get USB3/USBC/Thunderbolt docks now, so you can dock multiple monitors, wired network, your keyboard, your mouse (and on Thunderbolt a desktop GPU) with a single USB lead. It's pretty damn cool.