While I haven't seen those comparisons, I did do a similar one myself. Like GP, I have a 2013 mbp. It still works perfectly and handles whatever I throw at it. As it's getting long in the tooth and it could end up not working anymore, and also because I got curious with the release of the 16" mbp, I looked a bit at the market, and also at similar offerings from Lenovo, HP and Dell.
You are right, for the price of a 16" MBP with 64 GB RAM and 1 TB SSD, I could buy a maxed out Lenovo X1E with 2 SSDs, so I could dual boot windows and Linux (I use Photoshop / Lightroom for personal photography but can't stand Windows otherwise). Oh, and I'd probably have more than enough left to go on a trip somewhere and actually use the mobile part of the laptop.
So yes, on pure performance numbers, I completely agree. However, that's really not the whole story. Not everybody needs absolute maximum performance. I wouldn't still be happy with my 7 yo mac if I did.
I use my laptop every day for (hopefully) years and years. So I care about other things. First and most important of all, the touchpad. I've tried Lenovo (T series), Dell XPS and HP Elitebook models. They all absolutely suck compared to a mbp. A friend has a 2-3 yo Dell XPS. The palmrest plastic is all sticky, the screen is wobbly the touchpad is a nightmare (sometimes it clicks on its own). I have an HP from work I sometimes use. The junction between the palm rest and the body isn't level, so after a few hours of working on it my wrists are raw from rubbing on the body. The same laptop has a power light right in front of the screen that is blinding. I had to cover it with a piece of aluminum foil to be able to work in the evening. These kinds of annoyances make it worth it for me to spend the extra cash on a mbp that will just get out of my way and let me work.