I'd rather have them work/chat on their phones than pretend to be interested in listening to a manuscript being read that they have read before.
I think there's a problem here...
Actual lobbyists write actual legislation, in fact. And our politicians vote on them without having read it. It's a really stupid system.
Each politician has an office of staff behind them collating and feeding them updates. They have staff in that office monitoring the chamber feeds as well.
Disconnecting from that fire hose to only focus on the current speaker would not be as effective to consume all the different sources of information coming in during proceedings.