"Modest machine" LMAO, you mean complete junk. Mega-bad processor (as is standard for the cheapest laptops), 4gb ram, HDD. "Modest". Ok.
Linux Mint is slightly and almost imperceptibly faster than Windows 10, even though Windows 10 is handicapped by a resident AV.
Some of the data look suspicious for me. I agree booting may be way faster on Gnu/Linux system, but why opening the same document in LibreOffice is faster? I don't get it. Basic tasks can be done using that processor and that amount of RAM. At least on Gnu/Linux that amount of RAM is enough. I only think that HDD should be replaced for SSD, because SSD are quite cheap and difference is like night and day.
Take with a pinch of salt; the OP is taking extremely small dataset to make sweeping generalisation, which the original article manages to (almost until the end) avoid doing.
Well, yes, not exactly a representative sample of the population goes without saying: one. But still interesting that somebody bothered to state some metrics, don't you think?