With sites that only have a flat view I have to scroll through MANY pages of the thread to see the original reply that someone has replied to.
You don't have to scroll at all to get back to the post that someone is replying to. At the top of each post (except the OP) there is a line that says "In reply to <poster's name>". The poster's name is a link. If you click on that it will take you directly to that post (and if you want to get back to where you just came from, just click on the browser's back arrow).
The same is true in threaded view – unless dpr has given you a special editor.
You are making a complaint based on knowing little about how flat view works. You would probably be (rightly) critical of people who made similar complaints against threaded view.
Are you honestly telling us that the "In reply to . . . " field does not appear on the posts in threaded view on your computer/browser? Here is your reply to Mike_PEAT as seen in my computer in threaded view:

Post as seen in threaded view
First, apologies for my mistake about threaded view (and also apologies for not replying sooner. I had things to do in real life).
What happened was that I clicked on the threaded view button to check, and didn't realise that I'd been sent back to the start of the thread. The OP, of course, doesn't have "In reply to <poster's name>".