except for 2020 and no one as of yet as said why ?

The answer's been known for years. You just haven't cared to know that Republicans are to blame.

The issue would be, the results could be leaked early and then kill Election Day voting.

Then why does every other state outside of those controlled by Republicans do it then?

Please go back to China or stop posting here. You don't have a clue how our voting systems work. Any state can start counting mailed-in ballots as soon as they receive them and keep the results confidential until after the Election Day polls close. Again, you misconstrue how simple citizens - many who volunteer - take their responsibilities seriously when it comes to elections at all levels, mainly because elections make our democracy possible. Many states announce their early tallies with absolutely no appreciable impact on same-day turnout. And what good would early tally numbers do anyway?

Only people who don't understand that Americans vote one person at a time, making it impossible to inject non-registered voters into the process in sufficient numbers to sway any race. In conjunction, no one ever knows definitively where illegal voters would be needed.

Media is blockaded from releasing exit polling until after the polls close wherever the polling took place. GOP states even forbid starting the mail-in ballot count even on Election Day itself when a lot could be accomplished before the days votes are available for counting.

So consider yourself a tool, okay....

Only people who don't understand that Americans vote one person at a time, making it impossible to inject non-registered voters into the process in sufficient numbers to sway any race think our voting systems aren't secure. - correction

the results could be leaked early and then kill Election Day voting.

Which isn't a real thing. States either report early voting totals or they don't. In most states, mail-in voting tends to skew towards one party over the other. I've never seen it 50/50. So to use early tallies as a reason either to or not to vote on Election Day only reveals the lack of importance any such voter places upon their right to vote.

In places where elections are often close, voters know that their votes are important and would not base their decision whether to vote on Election Day (or anytime) upon what others have done before them.