Why?
Tired backs, achy knees, slow feet, spouses and children they had to crawl over to get out of the pew… Lots of well-meaning older people make it a point to be at the mass they were assigned to and will sit in a place where they can get to their spot. If your parishioners made sacrifices to serve (and many do), and nobody communicated to them that Fr. So-and-so was going to pop out of the sacristy for 10 minutes and then disappear after communion, or that 3 missionary deacons from Yakestoniezia would be visiting today, then displacing those trained, well-meaning, servants in such a manner could guarantee that their “assistance won’t be necessary in the future,” either.
That’s bad-news-Bob if your parish is trying to build a culture of stewardship.
I seem to remember a saying about gift horses and mouths.