So I just learned this recently, but apparently after the whole Victorian "smash and grab" thing where Britain stole all the art that was or wasn't nailed down (there's a lot of feet and footless statues lol), archeologists went to sites and realized how much knowledge was destroyed by their predecessors who only cared about impressive finds they could show off

Technology and techniques are always improving, so now when they find an archeological site, they excavate only a fraction, leaving the rest for future generations who will have better tools.

Obviously, non-destructive methods are still on the table, but I found that pretty interesting