Timezones matter. London is a financial hub because it's able to work with both the US east coast (NY) and also most of Asia-Pacific. NY and Asia-Pacific though is doable but tougher (12-13h difference).
The toughest is when you need to include folks from SF, London and HK [1]. There's just no good overlap. Either you rotate the suffering or you get disgruntled employees.
One solution is to decide which timezone is most important to you, and then restricting hiring +/- 6 hours from that timezone. Or split up synchronous meetings to two different sessions for two different sides of the world (this might lead to content bifurcation but may work in some instances).
It's a serious quality of life issue that employers ignore or downplay at their peril -- by not respecting timezones, employers are signaling they don't care. Employees on the short end of the stick with respect to timezone feel unimportant and excluded (first hand knowledge of this), especially if it's imposed from above without consultation.
Even small timezone differences are annoying -- I'm in Central Time and people in Eastern Time keep scheduling meetings around my lunchtime. The only way to get around this is to add fake calendar items around lunch time to block off that time.
[1] https://www.timeanddate.com/worldclock/meeting.html