yes, it is disputed, and the claim has not been tested in court. but it is an argument being made.
the GPL was primarily a weapon against BSD.
It's indeed a license that must be avoided at all cost.
well, it depend on whose side you support. i am on the side of protecting the rights of the user to modify their software. BSD licenses don't do that. they give me the right, but they don't protect it.
more importantly, i am also on the side of the developer to protect their ability to make a living. for that the BSD license is completely useless. GPL is better, AGPL even more, but even those are not restrictive enough to prevent unfair competition by large corporations.
i am not interested in allowing those companies to benefit from my work if they are not required to pass that forward.