Suppose you are a doctor so if you do not give treatment to the patients, people will ask you why you don’t give him treatment but if you give treatment no one will ask you because you have knowledge and talents that must be having it’s impact. Now another question being a doctor, you have your knowledge but when you visit to a patient obviously you will prescribe some medicine after checking the patient but here if you don’t do that, being a doctor will you lose your knowledge or if you don’t use tools of checking and pen and paper for writing the prescription who is going to loose, you being a doctor or your patient? Again who needs your knowledge, you yourself or your patient? Of course your patient but again in reality who was in need of all those instruments for examination., you or your patient? Logic says your patient because these tools are means for giving benefits to the patient otherwise your knowledge is constant whether you see a patient or not.
Allah (swt) says in Surah “Ikhlas” :

اللَّهُ الصَّمَدُ
Allah is He on Whom all depend.
He doesn’t need any angels or any Prophet but because we are limited to receive His blessings directly from Him therefore we need a connecting link. Let me clear it to you also that these restrictions are only here in this material world otherwise in paradise whatever a believer hasintended, it will appear without any mediator.
But this very World have one formula that is cause and effect and many times for achieving a goal we need many sub causes. Allah (swt) for our guidance sent Prophets and He commands His Prophets through His angels and because Prophets have power to receive Divine Commands from Angels and as they have material feelings and body to connect themselves with us also.
But yes Allah has power even to do all these without any means and mediator but then we will loose our free will and will become either like Angels or like animals therefore Allah after the creation of Human being says :

ثُمَّ خَلَقْنَا النُّطْفَةَ عَلَقَةً فَخَلَقْنَا الْعَلَقَةَ مُضْغَةً فَخَلَقْنَا الْمُضْغَةَ عِظَامًا فَكَسَوْنَا الْعِظَامَ لَحْمًا ثُمَّ أَنشَأْنَاهُ خَلْقًا آخَرَ فَتَبَارَكَ اللَّهُ أَحْسَنُ الْخَالِقِينَ

Then We made the seed a clot, then We made the clot a lump of flesh, then We made (in) the lump of flesh bones, then We clothed the bones with flesh, then We caused it to grow into another creation, so blessed be Allah, the best of the creators.(23:14)
So we Human can realize that there is a creation of Allah which has only intellect (angels) there is also creation of Allah which has only desires but no intellect ( Animal) and there is the third and unique creation of Allah which has both ( Human) therefore if human follows its desires despite having intellect will become lower than Animals and if dominant his intellect over his desires he will become superior than Angels.