Using Greek letters in names/on items

[OnAMission]

Hey all -

I recently was on Facebook and I saw a thing where some group used a sigma in place of an "e" in some of their lettering and got backlash about it because sigma is really equivalent to an "s."

Is that really a big deal? I've definitely seen some Greek groups or at least letting shops do that before, but I never thought about the significance of it.