It looks like at a masonic convention in the 1840s, concern was that after becoming an EA, some would only attend business meetings to gather information to publish anti-masonic books and articles.
From that time, it became the procedure in the USA to have meetings on the Master Masons Degree, only opening on the EA or FC degrees to initiate and advance members. When I have attended Lodge in England and Ireland, business was conducted on the EA degree.
There appears to be a movement in some grand lodges (mine included) to allow lodges, if they desired, to open on the First Degree for business, so that EAs and FCs could attend. There is the usual "But we've never done it that way!" resistance, though history actually contradicts this view.
S&F