Because I actually remember Djokovic almost reaching the semifinals in 2011 with 1 win. (1 very close win, and in one of his losses he was totally destroyed). But when it comes to Nadal he never gets out of the group unless he has 3 wins, and even then they try to find reasons to keep him out.
Let's see. I feel like tearing this apart.
The years Nadal played are 2006, 2007, 2009, 2010, 2011, 2013, 2015, 2017, 2019.
The only years he didn't get out of the RR were 2009, 2011, 2017 and 2019.
In 2009 he lost all three matches.
In 2011 he did the exact same as Djokovic which you were just complaining about: barely beating Fish, getting destroyed by Fed and losing a tight one to Tsonga. And Djokovic didn't make the semi, you calling it "almost" doesn't mean anything.
In 2017 he lost one tight match and just pulled out of the tournament, that's not the tournament's fault (nor are any other of his many withdrawals).
2019 is the only time he won two matches and didn't reach the semi, and even then the other two-match winners, yes including Fed, had better set win-loss records, helps that Fed won both his RR wins in straights which includes Djokovic.
In 2006 and 2007 he reached the semi's while losing a RR match. In 2010, 2013 and 2015 he reached the semi's because he won all three of his RR's,
makes sense doesn't it!