Chelsea and Arsenal have their own businesses, as does Manchester United. Ten Hag is a good coach, but the lack of players is the reason why Manchester United is still failing. If management can give him high confidence, then fans' calls to fire him may still be ignored, at least until next season ends.
I think Erik ten Hag is not short of players but just had bad luck with the many injuries that have plagued his players this season. This was certainly beyond predictions, so Manchester United could not secure a place in a bigger competition. However, with a win in the FA Cup at least they can still get the European league.
Last season was clearly their best season after finishing in the top four and participating in the champions league but this season everything was so out of control that they had no choice but to finish in mid-table. I think Erik ten Hag deserves to be given a chance and the need for additional adaptation for his players who don't have definite chemistry then that will be a job he has to complete.