Saying "giving everyone the right to share it" is contrary to the goal of having it be shared widely (aka adopted), is at least a gross oversimplification and at most an absurd statement.
However, RMS sees room for tactically using permissive licenses for the purpose of adoption too, http://www.gnu.org/philosophy/pragmatic.en.html
Getting more adoption as part of proprietary software may or may not lead to more overall adoption. Bsd kernel vs linux kernel is a case for gpl leading to more adoption than permissive. GPL says "allow EVERYONE to share it." And in some cases, more people share it this way! Who would have guessed? And it can lead to more people contributing, because they know everyone will have the right to share their work. The fact that permissive code means it could be shared LESS, because it can't be part of software which makes sharing illegal, is kind of across purposes. I mean, if you just care about adoption, a lot of times, you might get more by keeping it completely proprietary and selling the copyright to a big company. Or you might get more by embedding it into worms and phishing emails and running a botnet.