3k is pretty do-able for t7. what tank are you playing?
hell, earlier tonight i did 2600 with my tiger p against 5 t9's and many t8's (still lost )
If it was going to happen for me, it would probably be in my Tiger P. I also play a kv3 and su152, but generally don't deal as much damage with either as I do in the P. But, as in your example, a t7 has to be on or near the bottom of the match, otherwise there likely won't be enough enemy HP to go around. Plus, in a P you're only dealing damage in chunks of 240, that is a lot of shots you need to land.
Now I'm not saying it's not possible get 3k in a t7, but I am saying that it would be quite a feat. I barely pay any attention to my damage numbers, but I think 2k is a middling-high match for me, with a few scoring above 2500. But even if you disagree
completely with all of the above, you have to admit that it is far more common to have a 3k+ game in an E4, or even an IS7, than it is for any tier 7 (except maybe arty).