Well, if we're going to compare a 10U softball catcher's mechanics to a Major League Baseball catcher...no, let's don't!
Sure, catchers move and sometimes it does block your view. And some play right up on the plate, half stand up when a pitch is coming in, hold their gloves out when they go to grab a pitch or do lots of other stuff that makes it hard to see the pitch. When they do, you need to adjust for it.
It's usually only an issue with pitches that are right on the border and usually just the inside ones. "Right down the middle" with a kid that's barely five feet tall and pitches that might be hitting 45 m.p.h.? I can't see that throwing me off too much!
Catcher's can help their own cause by using good technique to receive pitches. The revese is, of course, also true. If you're blocking the plate you are probably going to cost your pitcher a few borderline calls. If that is happening, then the umpire should be able to articulate to the catcher or coach exactly what is happening and why. And a coach should be able to use that information to...coach his catcher.
In all but the most extreme cases, an umpire should be able to adjust. You work a little higher, a little further in or out, whatever it takes to see the plate. You are allowed to move around back there, ya know!
None of this is anything new- but it might be new to someone just starting out at the 10U level. It's a conversation I might have with a coach or catcher a couple of times a year. It's probably an issue that's come up ever since there were catchers catching pitches and umpires standing behind them to call the pitch.