https://www.thedrive.com/the-war-zone/20782/boeings-been-gra...
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You don't countersue a troll, because they have no assets. You might countersue a rival, except they probably won't sue you. Mutually Assured Destruction is the more common defense among competitors.
A countersuit against a rival would need at least some basis in reality, so they'd have to be selling something that infringed your patent (unlikely).
The are no suits because MAD works. MAD only works if both sides have enough ammo to glass the other. So you need all the patents you can get to have a reasonable chance of finding a few your opponent infringes upon.
It's much more complicated than you think. Sometimes MAD works, but sometimes the rivals do cross-licensing. "Getting more patents just in case we need them" is maybe one of the reasons, but there are so many others:
1) To protect the things we're already doing
2) To protect things we MIGHT do
3) Because that's what big companies do. Herd-following.
4) To keep someone else from horning in on our space
5) To use for cross-licensing or counter-suits
6) To sell in case we never want to commercialize
Don't underestimate #3. Every business "analyst" looks at your patent production.