And this is not safe and not being used properly.
Yes, you can get parts exactly the same size using traditional methods. It's done all the time in woodworking.
I've got 4, maybe 5 routers. My largest is PC's largest (and most expensive) and is a beast.
A friend of mine was an acrylic guru. Use to build windshields for boats. Large boats. (plus cabinets out of acrylic. This guy was good) Taught me the little I know about working with it. I've consistently gotten parts exactly the same size using normal wood working techniques. I've also done it the same way you have shown.
The way you are showing is NOT for a newbie who isn't 100% familiar with a router and how it can hurt the acrylic. Not to mention lost digits.
As for all the sheets being the same size. While true, all you have to do is lose concentration for a nano second and you'll have a divot. All the panels will be the same size though. And all the sides may be the right size. Without following proper technique at the saw you may find you have a parallelogram instead of a square/rectangle.
I'm no guru, just a simple man making his way in the universe.