“...I noticed they were only distributing the host to communicants, without offering the cup to drink from as well. When did that become practice?”
It was first commonly shared up until the High Middle Ages. Because of cost, worries about spilling the cup, and heretical groups like the Hussites, the practice ceased in the Late Middle Ages. It was revived experimentally in the 1950s in Europe if I am not mistaken. It became common in the U.S. in the 1970s with the permission of the Vatican (because such a practice is not explicitly seen in the rubrics of the Mass). That permission was believed by some to have ended in 2010. One diocese - Phoenix - tried to restrict the sharing of the cup (as would have been proper since the permission was believed to have expired), but the bishop (a good bishop, Bishop Olmstead) has apparently waffled on that because of the outcry from Mass goers: http://www.azcentral.com/arizonarepublic/news/articles/2011/11/11/20111111phoenix-bishop-reverses-ruling-wine-communion.html Apparently the permission was about a related matter and not the actual sharing of the cup. The sharing of the cup can only happen at the “new” liturgies: i.e. the new Mass since Vatican II and the Anglican Use Mass. It CAN NEVER happen at the old Latin Mass from before Vatican II.
Jesus said,' Drink of the cup'...
Well Lord, it just costs too much plus we don't want to get this expensive carpet dirty...So we'll just pretend there's blood in the bread...