Until this spring, I used a ~7 year old Dell Precision M4300 laptop.
Same here. I installed Arch for the very first time this summer on old hardware to make sure that I did not ruin my running Linux installations. Trying it in VirtualBox would probably have been a better option, but this seemed overly complicated at that time and I had this old laptop lying around. However, I think we still should consider having only UEFI in the beginners guide and link to a separate wiki entry if somebody needs an MBR partition. The reasoning is this: When I first installed Arch, I found the whole paragraph about partitioning the hard drive to be the most confusing one as it mentioned several partitioning tools and -schemes. This part of the beginner's guide has been rewritten since then and I find it to be much clearer now. Still, for the very noob I was half a year ago, it would probably have been easier to have UEFI as the default in the beginner's guide and MBR in a separate wiki.