It is not that weird to play in an empty stadium but if you add noise with the use of speakers then it will be pretty weird. I hate to say this, but i never expected we would see fake reactions but now the broadcasters wanted to add the crowd noise to add the flavor. I would like to hear the real conversation of the players rather than some fake reactions and with an empty stadium you could clearly hear what the players talk and a good commentary will sort the problem.
Players are used to hear crowd noise all the time in the middle of matches. I don't think they pay attention too much to it, but it's something they'll certainly feel is missing once they play alone, with nobody on the stadium besides the teams.Think of how it'd be to go and see a FIFA match live and you'd be the only fan there, all the other seats being silent and empty. Would feel very weird, wouldn't it? That noise is specific to these matches
You can roughly compare this to the clapping and laughing you hear on shows like BigBangTheory. 