My 2 cents (at the risk of stirring up stink from those that have differences of opinion.)
Depending on one's needs, there is absolutely nothing wrong with buying an OEM machine. I have built several custom machines for other people, but have zero need for elaborate hardware for myself so I use an OEM. I don't use a system for heavy lifting apps or gaming. Therefore, first take into consideration how you will use the computer.
One's needs is only one reason one might not want to mess with building his own. Not everyone is a geek and might not want to do it or maybe not have the time, know how, and experience to do it. Cash is another reason. Folks that have never built their own need to know there's a little more to it than just throwing the components into a case and firing it up. One has to know enough about hardware to buy exactly what is needed and be prepared for problems and know how to troubleshoot those problems.
As far as buying off of Ebay, I have purchased several hundred off lease business grade machines (all Precisions and Optiplexes) which I have rebuilt for resell. I have gotten only one that wasn't exactly as advertised. The seller immediately sent me another one. I have also run across ready to go systems for hella bargains. All I had to do was buy, test and then could immediately resell for a profit without me having to fix anything. The key is to purchase from sellers with a good reputation and to ask questions. Read the reviews. Nowadays, if there is a problem, Ebay will either make sure a seller stands behind the product or Ebay will refund your money. Therefore I would never tell anyone not to buy a refurbished system. Real bargains can be found.
Regarding the Precision you referenced, equipment wise it is a decent machine.It is not a gaming machine. Though it probably won't make any difference for some years, you should consider that the 8th gen CPU is the oldest one on MS Windows 11 compatibility list. No one knows when/if MS will drop that CPU from compatibility with future versions The large ssd and 32 gb ram are a big plus as is having PRO. Those exceed what one gets in most OEM machines you find on the shelf.
