Both of us are not making progress but others do. Maybe he is an ace trader in a cutter that by stopping or delaying him I make a dent in their overall progress. Maybe we also have an ace trader on our side that wasnt stopped and we are winning, this is a dynamic conflict rather than a grind war. You just want a grind competition and think its an exciting gameplay.
Go on now, extend the logic there. What are those guys doing? Some trying to stop people? Some working the BGS? Who will win ultimately? The answer is simple, those with more working the BGS. If you have more than enough players to stop another group in their tracks (which would be impossible considering timezones, instancing, etc) then you wouldn't need the PvP to win in the first place, you'd be win a lot quicker without the PvP.
Chances are, no matter how good you are at PvP, there is always the chance on a 1 to 1 basis that an opponent will get through. And once they do, that's it, you are behind in the BGS war. Assuming both sides are knowledgable about the BGS, then its just a numbers game. The more player hours you have in filling the various buckets, the more chance you have of winning. Ultimately, you're just losing time trying to stop people.
I know you want to point to rebuys, but is that really a deterrent these days? Anyone who wants credits already has billions. And to work the BGS you don't even need an expensive ship. You just need to know what you are doing. If in a situation where PvP is possible, a cheap fast ship is probably a lot more useful than a PvP warship. Don't waste your time fighting off PvPers, break the blockade and make your delivery and get on with the show.