As one of the largest ad blockers around they also try and extinguish any potential competition before it has a chance to establish itself.
When I initially released my ad blocker for the iPhone and Mac – Magic Lasso Adblock (https://www.magiclasso.co/) they attempted to stop its distribution through the Apple App Stores.
They sent legal threats directly to myself and then to Apple claiming that they own the term 'adblock' and demanded that my product stop using that term in any marketing or App Store keywords. This went on for months with them constantly pushing less and less plausible evidence for their ownership of the term.
I eventually told their enforcement loonies to stop contacting me and provided evidence to Apple that their claims are baseless (which meant their claims directly to Apple could also be ignored). They eventually stopped but I can see how their tactics could discourage any new entrants in the space.