Why this information is still available if it is well known that it encourage pool hopping and other attacks?
Is there any way that prevent miner to know this exact number of total already submitted shares?
e.g. PPLNS - knowing the numbers provides no information about getting a better or worse payout in the future.
You are probably reading about Prop or some other recent bazaar payouts being used where knowing the information does allow you to game the pool.
Most pools are not stupid enough to use such payout mechanisms.