Counterpoint - No.
NFL and College are spectator sports. High school has spectators, but it's still for the kids, first and foremost. It's important to give the explanation to coaches and teams as to what the foul was and how it's enforced, but it's not strictly necessary to inform the fans.
Since higher levels exist to get the fans to spend money, then you develop procedures to keep the fans interested and informed about the game. That's not to say microphones are a bad thing in high school, but it's not worth forcing an investment for every school.
Some real-life reasons why “yes.”
1. Had a playoff game last week and we had a late-game situation that required the game clock to be re-set. No field mic. Had to try to show fingers to the CO. After three INCORRECT resets, and about 2 full minutes (a football eternity), the clock finally got reset correctly. With a field mic, as I have done dozens of times before when I had a field mic, I could have flipped on the mic, announced the time to the put on the clock, and we could have been back to play in maybe 10 seconds, total.
2. Had a playoff game yesterday, at the same location, and we had dead-ball UNRs by both teams, with one player being disqualified. Couldn’t make an announcement of the DQ’d player’s number and reason for the DQ. The fans, and everybody else, deserve to know what was going on. Even if I wanted to, I can’t yell loud enough to let folks in the stands and pressbox know what is going on.
3. When a player’s helmet comes off, it is infinitely better to offer an explanation to the masses as to why he is leaving the game for one down.
4. For fouls that use S19, it is infinitely better to be able to announce the specific foul.
5. For UNS and UNR fouls, it is infinitely better to be able to announce the nature of the foul, i.e., late hit, taunting, etc.
I could list a dozen more. But I’ll stop there.
The cost of a simple but good referee’s field mic system is less than $4,000. That is a very small investment that will yield great returns.