It is a MAJOR issue! Lets say for example, this query is displaying a list of 150 orders, 20 per page or 7 1/2 pages.
The person looking at the list is responsible for reviewing each order and correcting them if necessary prior to shipping.
They go to the first order in line, no change click Back. They expect and it does return to page 1. They click the next order in line and continue thru the list.
Now they go to page 2 and click on the first item on that page. No charge just click the back button. It doesn't return to page 2 it returns to page 1 and they advance to page 2 find where they were in the list and click the next order. No change again, click back and now there back on page 1. They click advance again click on the next item, click back and find themselves back on page 1. Move to page 2 find the item click on it, click back and there back on page 1. And it goes on and on and on...
This can piss off a user in a matter of seconds. Have you ever tried it.
If there is any question in your mind how non productive this is, try it and around the 2nd or 3rd page of items you will agree that it is a MAJOR issue. While your at it, try taking a phone call in between and try to remember what item your on, was that the 3rd or 5th page? Crap your on page 1 maybe try starting over.
When someone clicks the Back button they expect to find themselves on the previous page and no where else. Its not a JUMP anywhere you want button.