Okay, let's be less vague then: Portugal, Belgium, Italy, Czechia, Slovakia, Norway, Sweden, Finland, Greece, Romania, Moldova, Mexico, and Egypt have mail voting only for citizens abroad.
France, Iceland, Croatia, Bulgaria, Serbia, Ukraine, Turkey, Israel, Morocco, Algeria, Tunisia, Nepal, Laos, Vietnam, Cambodia, Taiwan, Papua New Guinea, Madagascar, and every single country in South America (except Guyana and Suriname) have no mail voting whatsoever. As a glance at the map in the wiki article will reveal, this is not even half of the list.
Are all of them disenfranchising their voters, and failing to live up to the promises of democracy, specifically because of the lack of mail voting?
> Do you think Trump's restrictions will have no practical effect
I think even if he bans voting by mail entirely, it would be consistent with the majority of democracies in the world, and would not reduce democracy in any way. In fact it would strengthen it, because one can have more trust in the legitimacy of each vote. I grant that this part is subjective, but the consistency with other democracies is fact.