The biggest problem that I see with home field advantage is that fans no longer know when to get loud.
I’ll explain in the 80s and 90s when home field was huge, there was no technology for calling plays in. With the advances in QB helmet microphones, the OC can call a play with a kill and the mic doesn’t cut out until 15 seconds left on the play clock.
This means that fans should be at their loudest right after the play ends and not after teams break the huddle. By the time a team breaks the huddle, they know the play and the kill play in the huddle, and with the invention of silent counts, it really minimizes home crowd advantage. Throw in that the game has become pass happy, weather does play a factor especially in cold weather cities