Manchester united problem is something else because they have continued to change players and coaches since Fergie left the club but all to no avail. It's quite sad to witness a once giant of the game even at the world level to be so belittled by so many little teams because I believe if Manchester united were in good shape, crystal palace would never had won that game with such huge margin.
Yes, it has been almost 10 seasons since Manchester United was unable to win the Premier League title. The reason is, the last time Manchester United won the Premier League was in the 2012-2013 season. After that season, Manchester United never again won the Premier League, and in its best performance, Manchester United was only able to become runner up, in the 2017-2018/2020-2021 season. Then this season Manchester United's performance also be bad again, and they have the opportunity to finish in the middle of the Premier League standings. So if you think deeper, it was only during Sir Alex's time that Manchester United triumphed so well. At that time, Manchester United was really feared by all teams in the Premier League and the world.
Maybe at that time the only team that was able to provide a little resistance to Manchester United in the Premier League was Manchester City.
Apart from that, Manchester United's defeat to Crystal Palace is clear evidence that Manchester United is indeed weak at the moment. Maybe if Manchester United's performance wants to improve again, in my opinion Manchester United management must be right in choosing players and coaches. In essence, Manchester United's special team tasked with analyzing the talent of players who will be recruited/contracted must be even better. Likewise with the selection of coaches, the Manchester United analysis team must really understand what kind of coach suits the playing style of the players.
So what I can conclude is that the most likely reason why Manchester United has not been able to recover during these 10 seasons could be because the Manchester United analyst team has so far not been good at selecting players and coaches.