One more relevant point here:
Acts 1:3-5
3 "To whom also he shewed himself alive after his passion by many infallible proofs, being seen of them forty days, and speaking of the things pertaining to the kingdom of God:
4 And, being assembled together with them, commanded them that they should not depart from Jerusalem, but wait for the promise of the Father, which, saith he, ye have heard of me.
5 For John truly baptized with water; but ye shall be baptized with the Holy Ghost not many days hence."
The command of Jesus to the disciples all 11 was one thing, "commanded them that they should not depart from Jerusalem, but wait for the promise of the Father." what was the promise of the father? The Holy Spirit was coming to indwell and fill them. Until that point in Time they were not to do anything and yet what did impetuous Peter do?
Acts 1:21-23,
21 "Wherefore of these men which have companied with us all the time that the Lord Jesus went in and out among us,
22 Beginning from the baptism of John, unto that same day that he was taken up from us, must one be ordained to be a witness with us of his resurrection.
23 And they appointed two, Joseph called Barsabas, who was surnamed Justus, and Matthias."
The Holy Spirit inspired Luke and He gave us a clue, the people disciples chose two and then prayed God which of these two do we choose? How did they kknow God wanted either, what about someone else. Why these two?
First they were not to do anyhting but tarry in Jerusalem and Wait for the Holy Spirit, once the Holy Spirit was come He not they would have shown them the true replacement. That happened to be Paul not either of these men. This was done out of disobedience to what Christ had said, which was "wait for the promise of the Father," we have problems waiting upon the Lord ourselves sometimes. To be this invalidates anything done and scripture through inspiration of the Holy Spirit makes it clear who made the choice, "they appointed two." Here had God been guiding Luke by inspiration would have confirmed God's choice and said God chose not they chose!