> Like hardware manufacturers? I thought getting commercial users to contribute to the kernel was desirable?
Contribute to drivers, yes. Steer development of the kernel, no, IMO. The more they contribute, the more influence they gain. And a lot of the contributions are not hardware related at all.
> Didn't Torvalds himself reject GPL-3?
I don't know, I didn't follow this as I don't follow Linux news that closely anymore. I thought it was mainly about the way that it was introduced. But I think it's a much better license than GPL-2.
> Now I'm really confused. Why would businesses not like the BSD license? And they don't like GPL-3 either? Is GPL-2 the goldilocks license for them?
Businesses hate the BSD license because any code derived does not have to be open at all. So that means anything they contribute can be taken by their competitors and used in closed-source software. That's totally OK. Because of this there's only a few companies involved in BSD. Notably Netflix, the former Skype (before it was acquired by MS), and some smaller orgs like Netapp and iX that makes freenas/truenas.
Companies hate GPL-3 because their license gets revoked if a company uses its patents to attack GPLd software. It also stipulates some other things like that devices running GPL-3 software must also be open (e.g. no locked bootloaders etc). Very good things IMO. A lot of GPL-3's stipulations were triggered by real-world exploitation of free software. Examples: By TiVo (hence the name "anti-TiVoisation clause" for the open hardware thing). And the anti-patent clause was a direct result of Microsoft's patent attacks on Linux. No wonder Steve Ballmer hated the GPL-3 so much.
This is why Microsoft and most of the others hate it so much, they love giving open source lip service, but are not really open source companies. The GPL-2 gives them enough loopholes to get away with this. Many companies avoid GPL-3 licensed software at all costs, it was the driving force for bash not being updated (and replaced by zsh) on macOS for example.
Personally I think it would be better if FreeBSD was GPL-3d but BSD is not bad for me as a use that doesn't want too much corporate influence. After all, if a company makes a closed-source fork it doesn't impact me in any way. I won't use it anyway.