Go back and read the Avengers run with Gilgamesh and Reed and Sue Richards being part of the team. No matter what Cap did, Reed always figured out a way to save the day before him and basically made Cap's leadership look hollow compared to another (arguably better) leader and Cap would be verbally and tangibly jealous about it. Cap HATED Cyclops bossing up on him because Scott's words had truth behind them and he currently is having trouble dealing with Havoks leadership.
In those Avengers issues the problem was that Reed was so used to leading that he would make decisions and take action without letting anyone know. he was basically treating the Avengers like it was The Fantastic Four and Capt. America took issue with it.
And all of this nonsense about Captain America not being able to handle other people being in the leadership position is bullshyt. While he would sometimes take the lead in a battle situation he never undermined a team leader. He took a backseat to the fukking Wasp of all people when she first became Avengers chairperson.
What is going on now is that current writers are making the character act like that horrible Ultimate Cap that Mark Millar created instead of the 616 version and it doesn't work.
I must be the only one here who loves Cap
You are not alone, homie. Cap is that dude.