No one engaged in a BGS war and with some brain cells would do what I've read in this sub i.e. like searching all locations here and there or camping hours in a system waiting for a contact etc. [i.e. a "blockade"]... I mean there's no general case, as depending on the various situations/states certain actions and countermeasures might be taken. Intelligence is also a key factor...

in particular when numbers or TZs do not cope.
Exactly. And yet, this is what many of the "Oh, won't you think of the BGS" proponents claim... that the only way to "defend" their faction is to kill
anyone messing with
their faction.
True, but after parties take the rebuys some kind of settlement is usually reached... reason is that one can grind relentless weeks or months doing the same thing away from any human direct confrontation. But when the human element comes in to play, the reaction to a human/human confrontation drives to totally different behaviours.
If you can identify the other party, true. But the old 1-9-90 rule applies: 1% of the playerbase actively participates in forums, 3rd party sites, and other out of game communcation channels. 9% lurk, and the rest only play the game. Now, those with PvP inclinations tend to be in that 10% of "hard core" players, and those who engage in BGS manipulation tend to be the same, so there's considerable overlap.
This strategy also assumes that the opposition
cares about rebuys, as opposed to results. Personally, I view a tactical rebuy as similar to a donation: as long as I break even at the end of the session, it's all good. Given that this has been my philosophy since ED 1.0, when credits where much harder to get, you can probably guess how little I have to worry about operating at a loss these days.
Ultimately, a "BGS war" is all about filling your buckets faster than the opposition. What many of the "Oh, won't you think of the BGS?" proponents don't seem to understand is this: as long as the opposition keeps things nice and legal, killing them
may slow them down on filling
their buckets, but it also empties
yours, and rather quickly at that.
That's a trade that I, for one, am willing to make. I've found that "incoming" missions are much less efficient, time wise, than outgoing ones. So at worst, I'm trading failing
one incoming mission for a
much more effective hit to oppositions's influence and security status. Furthermore, what little influence gain that one mission would give would be diluted among
all the factions in a system, not just the faction I'm targeting. By playing in Open, I gain access to the
opposition's buckets as well as my own... but only if I get murdered by them. It's typically a "heads I win, tails you lose worse!" scenario to me.
But even though simply cooperating with my own murder by the opposition is the
better strategy, I still try to avoid the rebuy. Succeeding in safely arriving to my destination in the face of player opposition is
much more fun than maximizing my efficiency. And I would hope it would be a lot more fun for the opposition as well. I will always respect the desire to have fun over maximizing efficiency.