It just you ... who recognize it first publicly. It's a habit of MQ to tells nothing when deprecating something. Maybe broker tells MQ that some will provide economic calendar (ec) through news tab like in MT4 and some won't provide ec and ask MQ to get rid of it, or maybe it burden MT5 itself. Maybe this and that. EC was a good idea though.
Also gone at my side. Broker is ActivTrades.
Update: The documentation ( https://www.metatrader5.com/en/terminal/help/startworking/interface) says:
This tab may be missing if the economic calendar is disabled on a trade server.
I.e. - the broker has deactivated it.