System font engines (and browser stacks) may handle the parsing and display of certain glyphs differently. These differences are necessary, in general, to create fidelity with the underlying OS (so web content doesn’t "look wrong"). These differences reduce fidelity.
Matching the underlying OS increases fidelity, rather than reducing it it. Or, put another way: Way more users use multiple apps on the same machine than use the same app on multiple machines.
Matching the underlying OS increases fidelity, rather than reducing it it. Or, put another way: Way more users use multiple apps on the same machine than use the same app on multiple machines.