Maybe you are not updated on the roster status of those dream team you are mentioning. Lebron, Davis, Durant, Irving suffers injury and out for the game for a long time that result to there team poor performance on this season, They just got back again so obviously they will still need adjustment to get there performance calibrated again. Davis and Lebron just got back in the game last match of Lakers and they are facing a tight match just to get spot on play in match.
Yes, they were the star players of the team and there was no doubt about that, but I believed that the rest of the team would get some victories without the presence of these allstar players.
Injuries is an important variable that can be decisive in a game, such as what happened to the Suns last season or with Warriors in the 2018/2019 Finals against Raptors.
For the Lakers, they are done this season I mean literally done. They lost to the Nuggets and their remaining schedule will be very hard. I don't expect them to enter even the play-in tournament right now. 2 games below the Spurs and 3 games below the Pelicans. The Lakers need to win on their last 4 games to have a tiny bit of chance to tie with the Spurs.
With the Nets, they dropped to 10th spot and they are performing really bad since the return of Kyrie Irving to play in their homecourt. Kinda disappointing if you will ask me because many are betting that they are the ones that will at least go to NBA Finals but like you said, Nets and Lakers are performing way too low to our expectation or... maybe we just expected too much from them. Anyway, the Nets' final 4 games will be a little easier than Lakers as they will face HOU, NYK, CLE and IND. They are currently tied with the Hornets at 9th and 1 game below the Hawks so the final games for these 3 teams will be crucial.
Hmm... what you said is interesting, I believe the Lakers and Nets have a smallchance of qualifying for the playoffs, these last games they will have will be extremely decisive.
If these teams don't qualify for the playoffs this season, I look forward to them coming into the next season stronger and better structured compared to this limited season they've had.