I’m not too surprised by that - you don’t pay out a lot money if you haven’t got good reason. Norton, from days long ago wasn’t thought to be anything more than a pain in the rear.
Companies generally buy out companies because they have something that they haven’t got and a revamp of your own product must be high on the list. As you say many thought this would be Avast absorbed into Norton, but that didn’t happen. Norton has taken the better bits and incorporated (not invisibly) them into Norton.
But then along came Gen Digital and swallowed that as well, but I’m unsure if they are anything than a big shell:
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What does Gen Digital do? Now, Gen empowers people to live their digital lives safely, privately, and confidently today and for generations to come. We bring award-winning products and services in cybersecurity, online privacy and identity protection to nearly 500 million users in more than 150 countries.