I make a distinction between the sanctuary and the altar. Depending on the specific church layout, there can indeed be reasons for EMsHC to enter the sanctuary.
I would caution you about getting too worked up about this stuff. Yes, there are a lot of things that go on in a great many parishes during the celebration of the Mass that are not just a matter of differing personal preferences – they are actually wrong. Some are actual liturgical abuses, some are irregularities, but either way they are wrong.
The problem is, unless the pastor/administrator is courageous and driven enough to make changes – and many are not, ain’t nothing gonna improve – except perhaps the building of bitterness and hatred within your own self.
Logic doesn’t apply on this one. One would think the Mass, given its paramount importance, would be celebrated by the numbers as the Church defines. Unfortunately human qualities like ego, envy, indolence, cowardice and others, terribly complicate things. Unless you’re actually witnessing graviora delicta or the like, I’ve found it best to keep one’s eyes shut and just offer the pain up to God.
I’ve written a couple of articles for Adoremus over the years. Keep in mind their opinions hold no power within the Church.