NFL Helmet Radios

I've wondered whether football players have a communication system in their helmets, to allow the QB to call plays and request blockers and for the coach to send in plays.

According to Quora, only one player from each team, the QB (offense) or a defensive LB, can have speakers, and they're one-way (coach-to-player) only.

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The rules allow for the quarterback on each team to have a headset in their helmet. One defensive player also has one in their helmet. It is usually a linebacker. Only one helmet with a microphone [sic] is allowed on the field at a time. The green dots on the backs of the helmets signify that they have communication equipment in them. It is a one way system. The coach can say things in the player's ear, but not vice versa.  It is worth noting that this only applies to the NFL.

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It should also be noted that the headsets in the helmets are cut off when the play clock hits 15 seconds, and does not come back in until the play clock starts for the next play.  This way there can't be any coaching when the players are at the line of scrimmage and/or during the actual play.

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One interesting note is that if one team’s radio breaks, the other team must stop using theirs to maintain fairness in the competition.

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one nominated player on each unit (offense, defense and special teams) can wear a helmet with a radio receiver fitted (this has been in effect since 1994[1] , with the defense also allowed to have one since 2008). That’s always the starting QB on offense, but on the D it can vary - normally it’s the defensive captain who calls the signals (often the middle linebacker). There can be several helmets fitted with the kit, but only one player thus equipped from each team is permitted to be in the game at a time.

This seems like an unnaturally restrictive system.  Wouldn't 2-way radio communication between all the players -- and the coordinators overlooking the field -- make more sense?

I think the players are supposed to play, and that having the coach hold the quarterback's hand is pretty pathetic. I would prefer no radios at all.