A practical issue- if you have a world-distributed workforce or an international news agency, what's the best geographical location for the headquarters?
London has long benefitted from its position allowing its working day overlapping everywhere from the US West coast to Japan, even if barely at those extremes. Most of the world's population lies between UTC-5 and UTC+5 I believe.
I've certainly seen "most" used to mean "almost all", and it appears as though you're feeling a little annoyed to see it used that way because you consider it misleading.
I've also frequently seen "most" used to mean "a majority", though, in which case GP's use of the term is precisely consistent with the facts in their source.
Given India is UTC+5.5 and China is UTC+8, plus many other large countries are outside that range (Indonesia, Japan, Bangladesh, Mexico, Phillipines) I think you need to stretch it a bit
Given OP's 10 hour range, UTC+0 to UTC+10 is almost certainly going to be the 10 hour range that includes the most people. It includes all of Asia, Europe and Africa, and excludes both the Pacific and Atlantic oceans.
UTC+8 is all of China and UTC+5.5 is all of India, and in between are high population countries like Indonesia, Philippines, Vietnam, so UTC+5.5 to UTC+8 has to be included.
UTC+11 to UTC-8.5 is the Pacific Ocean and has maybe 10 million people total, while UTC+0 has >100 million in UK, Portugal and part of Western Africa so UTC+0 must be part of the range.
That only leaves the choice between UTC-1/2 and UTC+9/10. UTC-1 and UTC-2 have under a million with only a few small islands while UTC+10 has most of Papua New Guinea with 6 million.
Seconding the UK. I live in Edinburgh (Scotland) and I can meet with people from west coast US as far as China with very minor adjustments to my working day. I have natural half day overlaps with east coast US, and most of my day overlaps with major outsourcing locations (except the phillipines, but can be managed with a 1 hour adjustment)
Does this actually matter? Internet cabling vs magical straight lines would amount to less than 1 second difference, so emails/slack/discord/IRC/etc (basically anything except video chat) would barely notice.
